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Mark Dugopolski, College Algebra, 4th Edition
1. In 1999, cigarette consumption in the U.S. was 125 packs per capita. This rate of consumption was 5/8 of what it was in 1980. Find the rate of consumption in 1980.
2. Freeport McMoRan projects that in 2010 world grain supply will be 1.8 trillion metric tons and the supply will be only ¾ of world grain demand. What will world grain demand be in 2010?
3. On Thursday,13/25 of the stocks traded on the New York Stock Exchange advanced in price. If 1495 stocks advanced, then how many stocks were traded on that day?
4. In 1996, 23/50 of all accidental deaths in the U.S. were the result of automobile accidents (National Center for Health Statistics, www.nchs.gov). If there were 43,194 deaths due to automobile accidents, then how many accidental deaths were there in 1996?
5. A lawyer charges $300 plus $65 per hour for a divorce. If the total charge for Bill’s divorce was $1405, then for what number of hours did the lawyer work on the case?
6. A plumber charges $45 plus $26 per hour to unclog drains. If the bill for unclogging Tamika’s drain was $123, then for how many hours did the plumber work?
7. If the air temperature in Quebec is 68° Fahrenheit, then the solution to the equation (9/5)C + 32 = 68 gives the Celsius temperature of the air. Find the Celsius temperature.
8. If a rectangular patio has a length that is 3 feet longer than its width and a perimeter of 42 feet, then the width can be found by solving the equation 2x + 2(x+3)= 42. What is the width?
9. The perimeter of the triangle shown in the accompanying figure is 12 meters. Determine the values of x, x + 1, and x + 2 by solving the equation x + (x + 1) + (x + 2) = 12.
10. Jane paid 9% sales tax and a $150 title and license fee when she bought her new Saturn for a total of $16,009.50. If x represents the price of the car, then x satisfies x + 0.09x + 150 = 16,009.50. Find the price of the car by solving the equation.
11. An electrician charged Eunice $29.96 for a service call plus $39.96 per hour for a total of $169.82 for installing her electric dryer. If n represents the number of hours for labor, then n satisfies 39.96n + 29.96 = 169.82. Find n by solving this equation.
12. Danielle sold her house through an agent who charged 8% of the selling price. After the commission was paid, Danielle received $117,760. If x is the selling price, then x satisfies x – 0.08x = 117,760 Solve this equation to find the selling price.
13. Before Roland sold two female rabbits, half of his rabbits were female. After the sale, only onethird of his rabbits were female. If x represents his original number of rabbits, then 1/2x – 2 = 1/3(x – 2). Solve this equation to find the number of rabbits that he had before the sale.
14. Reginald overheard his boss complaining that his federal income tax for 2000 was $34,276. a) Use the accompanying graph to estimate his boss’s taxable income for 2000. b) Find his boss’s exact taxable income for 2000 by solving the equation 23,965.5 + 0.31(x – 105,950) = 34,276
15. According to Bruce Harrell, CPA, the federal income tax for a class C corporation is found by solving a linear equation. The reason for the equation is that the amount x of federal tax is deducted before the state tax is figured, and the amount of state tax is deducted before the federal tax is figured. To find the amount of federal tax for a corporation with a taxable income of $200,000, for which the federal tax rate is 25% and the state tax rate is 10%, Bruce must solve
x = 0.25[200,000 – 0.10(200,000 – x)].
16. If the simple interest on $5000 for 3 years is $600, then what is the rate?
17. Wayne paid $420 in simple interest on a loan of $1000 for 7 years. What was the rate?
18. Kathy paid $500 in simple interest on a loan of $2500. If the annual interest rate was 5%, then what was the time?
19. Robert paid $240 in simple interest on a loan of $1000. If the annual interest rate was 8%, then what was the time?
20. The area of a rectangle is 28 square yards. The width is 4 yards. Find the length.
21. The area of a rectangle is 60 square feet. The length is 4 feet. Find the width.
22. If it takes 600 feet of wire fencing to fence a rectangular feed lot that has a width of 75 feet, then what is the length of the lot?
23. If it takes 500 feet of fencing to enclose a rectangular lot that is 104 feet wide, then how deep is the lot?
24. Find the original price if there is a 15% discount and the sale price is $255.
25. Find the list price if there is a 12% discount and the sale price is $4400.
26. Find the rate of discount if the discount is $40 and the original price is $200.
27. Find the rate of discount if the discount is $20 and the original price is $250.
28. The perimeter of a football field in the NFL, excluding the end zones, is 920 feet. How wide is the field?
29. If a picture frame is 16 inches by 20 inches, then what is its perimeter?
30. A rectangular box measures 2 feet wide, 3 feet long, and 4 feet deep. What is its volume?
31. The volume of a rectangular refrigerator is 20 cubic feet. If the top measures 2 feet by 2.5 feet, then what is the height?
32. If the circumference of a pizza is 8π inches, then what is the radius?
33. If the circumference of a circle is 4 π meters, then what is the diameter?
34. If a banner in the shape of a triangle has an area of 16 square feet with a base of 4 feet, then what is the height of the banner?
35. If a right triangle has an area of 14 square meters and one leg is 4 meters in length, then what is the length of the other leg?
36. A trapezoid with height 20 inches and lower base 8 inches has an area of 200 square inches. What is the length of its upper base?
37. The end of a flower box forms the shape of a trapezoid. The area of the trapezoid is 300 square centimeters. The bases are 16 centimeters and 24 centimeters in length. Find the height.
38. Doctors often prescribe the same drugs for children as they do for adults. The formula d=0.08aD (Fried’s rule) is used to calculate the child’s dosage d, where a is the child’s age and D is the adult dosage. If a doctor prescribes 1000 milligrams of acetaminophen for an adult, then how many milligrams would the doctor prescribe for an eightyearold child? Use the bar graph to determine the age at which a child would get the same dosage as an adult.
39. Cowling’s rule is another method for determining the dosage of a drug to prescribe to a child. For this rule, the formula d = D(a+1)/24 gives the child’s dosage d, where D is the adult dosage and a is the age of the child in years. If the adult dosage of a drug is 600 milligrams and a doctor uses this formula to determine that a child’s dosage is 200 milligrams, then how old is the child?
40. A patient is to receive 750 mg of the antibiotic Vancomycin. However, Vancomycin comes in a solution containing 1 gram (available dose) of Vancomycin per 5 milliliters (quantity) of solution. Use the formula Amount = (desired dose/available dose) ×quantity to find the amount to find the amount of this solution that should be administered to the patient.
41. The global investment in telecom infrastructure since 1990 can be modeled by the formula I = 7.5t +115 where I is in billions of dollars and t is the number of years since 1990 (Fortune, September 8, 1997). See the accompanying figure. a) Use the formula to find the global investment in 1994. b) Use the formula to predict the global investment in 2001. c) Find the year in which the global investment will reach $250 billion.
42. A 2.4meter sailboat is a oneperson boat that is about 13 feet in length, has a displacement of about 550 pounds, and a sail area of about 81 square feet. To compete in the 2.4meter class, a boat must satisfy the formula 2.4 = (L + 2D  F√S)/2.37 where L = length, F = freeboard, D = girth, and S = sail area. Solve the formula for L.
43.The distance, given that the rate is x miles per hour and the time is 3 hours
44. The distance, given that the rate is x + 10 miles per hour and the time is 5 hours
45. The discount, given that the rate is 25% and the original price is q dollars
46. The discount, given that the rate is 10% and the original price is t yen
47. The time, given that the distance is x miles and the rate is 20 miles per hour
48. The rate, given that the distance is x – 100 meters and the time is 12 seconds
49. Two numbers differ by 6 and have a product of –9
50. Herman’s house sold for x dollars. The real estate agent received 7% of the selling price, and Herman received $84,532.
51. Gwen sold her car on consignment for x dollars. The saleswoman’s commission was 10% of the selling price, and Gwen received $6570.
52. What percent of 500 is 100?
53. What percent of 40 is 120?
54. The value of x nickels and x + 2 dimes is $3.80.
55. The value of d dimes and d – 3 quarters is $6.75.
56. The sum of three consecutive integers is 42.
57. The sum of three consecutive odd integers is 27.
58. The product of two consecutive integers is 182.
59. The product of two consecutive even integers is 168.
60. Twelve percent of Harriet’s income is $3000.
61. If 9% of the members buy tickets, then we will sell 252 tickets to this group.
62. Thirteen is 5% of what number?
63. Three hundred is 8% of what number?
64. The length of a rectangle is 5 feet longer than the width, and the area is 126 square feet.
65. The length of a rectangle is 1 yard shorter than twice the width, and the perimeter is 298 yards.
66. The value of n nickels and n – 1 dimes is 95 cents.
67. The value of q quarters, q + 1 dimes, and 2q nickels is 90 cents.
68. The measure of an angle is 38° smaller than the measure of its supplementary angle.
69. The measure of an angle is 16° larger than the measure of its complementary angle.
70. For a cardiovascular work out, fitness experts recommend that you reach your target heart rate and stay at that rate for at least 20 minutes (Cycling, Burkett and Darst).To find your target heart rate, find the sum of your age and your resting heart rate, then subtract that sum from 220. Find 60% of that result and add it to your resting heart rate. a) Write an equation with variable r expressing the fact that the target heart rate for 30yearold Bob is 144. b) Judging from the accompanying graph, does the target heart rate for a 30yearold increase or decrease as the resting heart rate increases.
71. The saddle height on a bicycle should be 109% of the rider’s inside leg measurement L (Cycling, Burkett and Darst). See the figure. Write an equation expressing the fact that the saddle height for Brenda is 36 in.
72. Find three consecutive integers whose sum is 141.
73. Find three consecutive even integers whose sum is 114.
74. Two consecutive odd integers have a sum of 152. What are the integers?
75. Four consecutive odd integers have a sum of 120. What are the integers?
76. Find four consecutive integers whose sum is 194.
77. If an Olympic swimming pool is twice as long as it is wide and the perimeter is 150 meters, then what are the length and width?
78. If the perimeter of a tennis court is 228 feet and the length is 6 feet longer than twice the width, then what are the length and width?
79. Julia framed an oil painting that her uncle gave her. The painting was 4 inches longer than it was wide, and it took 176 inches of frame molding. What were the dimensions of the picture?
80. Geraldo drove his truck from Indianapolis to Chicago, then to St. Louis, and then back to Indianapolis. He observed that the second side of his triangular route was 81 miles short of being twice as long as the first side and that the third side was 61 miles longer than the first side. If he traveled a total of 720 miles, then how long is each side of this triangular route?
81. A banner in the shape of an isosceles triangle has a base that is 5 inches shorter than either of the equal sides. If the perimeter of the banner is 34 inches, then what is the length of the equal sides?
82. Dr. Good’s waiting room is 8 feet longer than it is wide. When Vincent wallpapered Dr. Good’s waiting room, he used 88 feet of border paper. What are the dimensions of Dr. Good’s waiting room?
83. A civil engineer is planning a highway overpass as shown in the figure. Find the degree measure of the angle marked w.
84. For the other side of the overpass, the engineer has drawn the plans shown in the figure. Find the degree measure of the angle marked z.
85. Bret drove for 4 hours on the freeway, then decreased his speed by 20 miles per hour and drove for 5 more hours on a country road. If his total trip was 485 miles, then what was his speed on the freeway?
86. On Saturday morning, Lynn walked for 2 hours and then ran for 30 minutes. If she ran twice as fast as she walked and she covered 12 miles altogether, then how fast did she walk?
87. Kathryn drove her rig 5 hours before dawn and 6 hours after dawn. If her average speed was 5 miles per hour more in the dark and she covered 630 miles altogether, then what was her speed after dawn?
88. On Monday, Roger drove to work in 45 minutes. On Tuesday he averaged 12 miles per hour more, and it took him 9 minutes less to get to work. How far does he travel to work?
89. A jet flew at an average speed of 640 mph from Los Angeles to Chicago. Because of head winds the jet averaged only 512 mph on the return trip, and the return trip took 48 minutes longer. How many hours was the flight from Chicago to Los Angeles? How far is it from Chicago to Los Angeles?
90. Penny’s bicycle trip from Colorado Springs to Pikes Peak took 1.5 hours longer than the return trip to Colorado Springs. If she averaged 6 mph on the way to Pikes Peak and 15 mph for the return trip, then how long was the ride from Colorado Springs to Pikes Peak?
91. The 1977 Super Bowl was played in the Rose Bowl in Pasadena. In that football game the Oakland Raiders scored 18 more points than the Minnesota Vikings. If the total number of points scored was 46, then what was the final score for the game?
92. Revenues for the top three companies in 1997, General Motors, Ford, and Exxon, totaled $453 billion (Fortune 500 List, www.fortune.com). If Ford’s revenue was $31 billion greater that Exxon’s, and General Motor’s revenue was $25 billion greater than Ford’s, then what was the 1997 revenue for each company?
93. Before lunch, Sally drove from Idabel to Ardmore, averaging 50 mph. After lunch she continued on to Lawton, averaging 53 mph. If her driving time after lunch was 1 hour less than her driving time before lunch and the total trip was 256 miles, then how many hours did she drive before lunch? How far is it from Ardmore to Lawton?
94. On Monday, Chuck drove from Norfolk to Valentine, averaging 47 mph. On Tuesday, he continued on to Chadron, averaging 69 mph. His driving time on Monday was 2 hours longer than his driving time on Tuesday. If the total distance from Norfolk to Chadron is 326 miles, then how many hours did he drive on Monday? How far is it from Valentine to Chadron?
95. Joan Crawford, John Wayne, and James Stewart were born in consecutive years (Doubleday Almanac). Joan Crawford was the oldest of the three, and James Stewart was the youngest. In 1950, after all three had their birthdays, the sum of their ages was 129. In what years were they born?
96. Bob Hope was born 2 years after Clark Gable and 2 years before Henry Fonda (Doubleday Almanac). In 1951, after all three of them had their birthdays, the sum of their ages was 144. In what years were they born?
97. A carpenter used 30 ft of molding in three pieces to trim a garage door. If the long piece was 2 ft longer than twice the length of each shorter piece, then how long was each piece?
98. Clint is constructing two adjacent rectangular dog pens. Each pen will be three times as long as it is wide, and the pens will share a common long side. If Clint has 65 ft of fencing, what are the dimensions of each pen?
99. At a 25% off sale, Jose saved $80 on a 19inch Panasonic TV. What was the original price of the television.
100. A 12% discount on a Giant Perigee saved Melanie $46.68. What was the original price of the bike?
101. After getting a 20% discount, Robert paid $320 for a Pioneer CD player for his car. What was the original price of the CD player?
102. After getting a 15% discount on the price of a new Chrysler Sebring convertible, Helen paid $27,000. What was the original price of the convertible?
103. Kirk wants to get $72,000 for his house. The real estate agent gets a commission equal to 10% of the selling price for selling the house. What should the selling price be?
104. Gene is selling his palomino at an auction. The auctioneer’s commission is 10% of the selling price. If Gene still owes $810 on the horse, then what must the horse sell for so that Gene can pay off his loan?
105. Merilee sells tomatoes at a roadside stand. Her total receipts including the 7% sales tax were $462.24. What amount of sales tax did she collect?
106. Gwen bought a new Toyota Corolla. The selling price plus the 8% state sales tax was $15,714. What was the selling price?
107. Wiley invested some money in the Berger 100 Fund and $3000 more than that amount in the Berger 101 Fund. For the year he was in the fund, the 100 Fund paid 18% simple interest and the 101 Fund paid 15% simple interest. If the income from the two investments totaled $3750 for one year, then how much did he invest in each fund?
108. Becky lent her brother some money at 8% simple interest, and she lent her sister twice as much at twice the interest rate. If she received a total of 20 cents interest, then how much did she lend to each of them?
109. David split his $25,000 inheritance between Fidelity ShortTerm Bond Fund with an annual yield of 5% and T. Rowe Price TaxFree ShortIntermediate Fund with an annual yield of 4%. If his total income for one year on the two investments was $1140, then how much did he invest in each fund?
110. Of the $50,000 that Natasha pocketed on her last real estate deal, $20,000 went to charity. She invested part of the remainder in Dreyfus New Leaders Fund with an annual yield of 16% and the rest in Templeton Growth Fund with an annual yield of 25%. If she made $6060 on these investments in one year, then how much did she invest in each fund?
111. How many gallons of milk containing 1% butterfat must be mixed with 30 gallons of milk containing 3% butterfat to obtain a mixture containing 2% butterfat?
112. How many gallons of a 5% acid solution should be mixed with 30 gallons of a 10% acid solution to obtain a mixture that is 8% acid?
113. Gus has on hand a 5% alcohol solution and a 20% alcohol solution. He needs 30 liters of a 10% alcohol solution. How many liters of each solution should he mix together to obtain the 30 liters?
114. Angela needs 20 quarts of 50% antifreeze solution in her radiator. She plans to obtain this by mixing some pure antifreeze with an appropriate amount of a 40% antifreeze solution. How many quarts of each should she use?
115. If 60% of the registered voters of Lancaster County voted in the November election and 33,420 votes were cast, then how many registered voters are there in Lancaster County?
116. Tough on crime. In a random sample of voters, 594 respondents said that they favored passage of a $33 billion crime bill. If the number in favor of the crime bill was 45% of the number of voters in the sample, then how many voters were in the sample?
117. Ford Taurus. At an 8% sales tax rate, the sales tax on Peter’s new Ford Taurus was $1200. What was the price of the car?
118. Taxpayer blues. Last year, Faye paid 24% of her income to taxes. If she paid $9600 in taxes, then what was her income?
119. Making a profit. A retail store buys shirts for $8 and sells them for $14. What percent increase is this?
120. Monitoring AIDS. If 28 new AIDS cases were reported in Landon County this year and 35 new cases were reported last year, then what percent decrease in new cases is this?
121. High school integration. Wilson High School has 400 students, of whom 20% are African American. The school board plans to merge Wilson High with Jefferson High. This one school will then have a student population that is 44% African American. If Jefferson currently has a student population that is 60% African American, then how many students are at Jefferson?
122. Junior high integration. The school board plans to merge two junior high schools into one school of 800 students in which 40% of the students will be Caucasian. One of the schools currently has 58% Caucasian students; the other has only 10% Caucasian students. How many students are in each of the two schools?
123. Hospital capacity. When Memorial Hospital is filled to capacity, it has 18 more people in semiprivate rooms (two patients to a room) than in private rooms. The room rates are $200 per day for a private room and $150 per day for a semiprivate room. If the total receipts for rooms is $17,400 per day when all are full, then how many rooms of each type does the hospital have?
124. Public relations. Memorial Hospital is planning an advertising campaign. It costs the hospital $3000 each time a television ad is aired and $2000 each time a radio ad is aired. The administrator wants to air 60 more television ads than radio ads. If the total cost of airing the ads is $580,000, then how many ads of each type will be aired?
125. Mixed nuts. Cashews sell for $4.80 per pound, and pistachios sell for $6.40 per pound. How many pounds of pistachios should be mixed with 20 pounds of cashews to get a mixture that sells for $5.40 per pound?
126. Premium blend. Premium coffee sells for $6.00 per pound, and regular coffee sells for $4.00 per pound. How many pounds of each type of coffee should be blended to obtain 100 pounds of a blend that sells for $4.64 per pound?
127. Nickels and dimes. Candice paid her library fine with 10 coins consisting of nickels and dimes. If the fine was $0.80, then how many of each type of coin did she use?
128. Dimes and quarters. Jeremy paid for his breakfast with 36 coins consisting of dimes and quarters. If the bill was $4.50, then how many of each type of coin did he use?
129. Cooking oil. Crisco Canola Oil is 7% saturated fat. Crisco blends corn oil that is 14% saturated fat with Crisco Canola Oil to get Crisco Canola and Corn Oil, which is 11% saturated fat. How many gallons of corn oil must Crisco mix with 600 gallons of Crisco Canola Oil to get Crisco Canola and Corn Oil?
130. Chocolate ripple. The Delicious Chocolate Shop makes a dark chocolate that is 35% fat and a white chocolate that is 48% fat. How many kilograms of dark chocolate should be mixed with 50 kilograms of white chocolate to make a ripple blend that is 40% fat?
131. Hawaiian Punch. Hawaiian Punch is 10% fruit juice. How much water would you have to add to one gallon of Hawaiian Punch to get a drink that is 6% fruit juice?
132. VCRs and CDs. The manager of a stereo shop placed an order for $10,710 worth of VCRs at $120 each and CD players at $150 each. If the number of VCRs she ordered was three times the number of CD players, then how many of each did she order?
133. Car shopping. Jennifer is shopping for a new car. In addition to the price of the car, there is an 8% sales tax and a $172 title and license fee. If Jennifer decides that she will spend less than $10,000 total, then what is the price range for the car?
134. Sewing machines. Charles wants to buy a sewing machine in a city with a 10% sales tax. He has at most $700 to spend. In what price range should he look?
135. Truck shopping. Linda and Bob are shopping for a new truck in a city with a 9% sales tax. There is also an $80 title and license fee to pay. They want to get a good truck and plan to spend at least $10,000. What is the price range for the truck?
136. Curly’s contribution. Larry, Curly, and Moe are going to buy their mother a color television set. Larry has a better job than Curly and agrees to contribute twice as much as Curly. Moe is unemployed and can spare only $50. If the kind of television Mama wants costs at least $600, then what is the price range for Curly’s contribution?
137. Renting a Mustang. Hillary can rent a Ford Mustang from Alpha Car Rental for $45 per day with no charge for miles. From Beta Car Rental she can get the same car for $35 per day plus 25 cents per mile. For what number of daily miles is Beta cheaper?
138. Renting a Cadillac. George can rent a Cadillac from Gamma Car Rental for $50 per day plus 35 cents per mile. He can get the same car from Delta Car Rental for $35 per day plus 45 cents per mile. For what number of daily miles is Delta cheaper?
139. Bachelor’s degrees. The graph shows the number of bachelor’s degrees awarded in the United States each year since 1985 (National Center for Education Statistics, www.nces.ed.gov). a) Has the number of bachelor’s degrees been increasing or decreasing since 1985? b) The formula B = 16.45n + 980.20 can be used to approximate the number of degrees awarded in thousands in the year 1985 + n. What is the first year in which the number of bachelor’s degrees will exceed 1.3 million?
140. Master’s degrees. In 1985, 15.9% of all degrees awarded in U.S. higher education were master’s degrees (National Center for Education Statistics). If the formulas M = 7.79n + 287.87 and T = 30.95n + 1808.22 give the number of master’s degrees and the total number of higher education degrees awarded in thousands, respectively, in the year 1985 + n, then what is the first year in which more than 20% of all degrees awarded will be master’s degrees?
141. Weighted average. Professor Jorgenson gives only a midterm exam and a final exam. The semester average is computed by taking 1/3 of the midterm exam score plus 2/3 of the final exam score. The grade is determined from the semester average by using the grading scale given in the table. If Stanley scored only 56 on the midterm, then for what range of scores on the final exam would he get a C or better in the course?
142. C or better. Professor Brown counts her midterm as 2/3 of the grade and her final as 1/3 of the grade. Wilbert scored only 56 on the midterm. If Professor Brown also uses the grading scale given in the table, then what range of scores on the final exam would give Wilbert a C or better in the course?
143. Designer jeans. A pair of ordinary jeans at AMart costs $50 less than a pair of designer jeans at Enrico’s. In fact, you can buy four pairs of AMart jeans for less than one pair of Enrico’s jeans. What is the price range for a pair of AMart jeans?
144. United Express. Al and Rita both drive parcel delivery trucks for United Express. Al averages 20 mph less than Rita. In fact, Al is so slow that in 5 hours he covered fewer miles than Rita did in 3 hours. What are the possible values for Al’s rate of speed?
145. Aiming for a C. Professor Johnson gives only a midterm exam and a final exam. The semester average is computed by taking 1/3 of the midterm exam score plus 2/3 of the final exam score. To get a C, Beth must have a semester average between 70 and 79 inclusive. If Beth scored only 64 on the midterm, then for what range of scores on the final exam would Beth get a C?
146. Two tests only. Professor Davis counts his midterm as 2/3 of the grade, and his final as 1/3 of the grade. Jason scored only 64 on the midterm. What range of scores on the final exam would put Jason’s average between 70 and 79 inclusive?
147. Keep on truckin’. Abdul is shopping for a new truck in a city with an 8% sales tax. There is also an $84 title and license fee to pay. He wants to get a good truck and plans to spend at least $12,000 but no more than $15,000. What is the price range for the truck?
148. Sellingprice range. Renee wants to sell her car through a broker who charges a commission of 10% of the selling price. The book value of the car is $14,900, but Renee still owes $13,104 on it. Although the car is in only fair condition and will not sell for more than the book value, Renee must get enough to at least pay off the loan. What is the range of the selling price?
149. Hazardous to her health. Trying to break her smoking habit, Jane calculates that she smokes only three full cigarettes a day, one after each meal. The rest of the time she smokes on the run and smokes only half of the cigarette. She estimates that she smokes the equivalent of 5 to 12 cigarettes per day. How many times a day does she light up on the run?
150. Possible width. The length of a rectangle is 20 meters longer than the width. The perimeter must be between 80 and 100 meters. What are the possible values for the width of the rectangle?
151. Higher education. The annual numbers of bachelor’s and master’s degrees awarded can be approximated using the formulas B = 16.45n + 980.20 and M = 7.79n + 287.87, where n is the number of years after 1985 (National Center for Education Statistics, ww.nces.ed.gov). For example, n = 2 gives the numbers in 1987. a) How many bachelor’s degrees were awarded in 1995? b) In what year will the number of bachelor’s degrees that are awarded reach 1.26 million?
c) What is the first year in which both B is greater than 1.3 million and M is greater than 0.5 million? d) What is the first year in which either B is greater than 1.3 million or M is greater than 0.5 million?
152. Senior citizens. The number of senior citizens (65 years old and over) in the United States in millions in the year 1970 + n can be estimated by using the formula S = 0.48n + 19.71 (U.S. Bureau of the Census, www.census.gov). The percentage of senior citizens living below the poverty level in the year 1970 + n can be estimated by using the formula p = –0.72n + 24.2. The variable n is the number of years after 1970. a) How many senior citizens were there in 1998?
b) In what year did the percentage of seniors living below the poverty level reach 2.6%? c) What is the first year in which we can expect both the number of seniors to be greater than 36 million and fewer than 2.6% living below the poverty level?
153. Famous battles. In the Hundred Years’ War, Henry V defeated a French army in the battle of Agincourt and Joan of Arc defeated an English army in the battle of Orleans (The Doubleday Almanac). Suppose you know only that these two famous battles were 14 years apart and that the battle of Agincourt occurred in 1415. Use an absolute value equation to find the possibilities for the year in which the battle of Orleans occurred.
154. World records. In July 1985 Steve Cram of Great Britain set a world record of 3 minutes 29.67 seconds for the 1500meter race and a world record of 3 minutes 46.31 seconds for the 1mile race (The Doubleday Almanac). Suppose you know only that these two events occurred 11 days apart and that the 1500meter record was set on July 16. Use an absolute value equation to find the possible dates for the 1mile record run.
155. Weight difference. Research at a major university has shown that identical twins generally differ by less than 6 pounds in body weight. If Kim weighs 127 pounds, then in what range is the weight of her identical twin sister Kathy?
156. Intelligence quotient. Jude’s IQ score is more than 15 points away from Sherry’s. If Sherry scored 110, then in what range is Jude’s score?
157. Unidentified flying objects. The formula S = –16t2 + vot + so gives height in feet above the earth at time t seconds for an object projected into the air with an initial velocity of vo feet per second (ft/sec) from an initial height of so feet. Two balls are tossed into the air simultaneously, one from the ground at 50 ft/sec and one from a height of 10 feet at 40 ft/sec. See the accompanying graph. a) Use the graph to estimate the time at which the balls are at the same height.
b) Find the time from part (a) algebraically. c) For what values of t will their heights above the ground differ by less than 5 feet (while they are both in the air)?
158. Playing catch. A circus clown at the top of a 60foot platform is playing catch with another clown on the ground. The clown on the platform drops a ball at the same time as the one on the ground tosses a ball upward at 80 ft/sec. For what length of time is the distance between the balls less than or equal to 10 feet? (Hint: Use the formula given in Exercise 89. The initial velocity of a ball that is dropped is 0 ft/sec.)
159. Percentage of full benefit. The age at which you retire affects your Social Security benefits. The accompanying graph gives the percentage of full benefit for each age from 62 through 70, based on current legislation and retirement after the year 2005 (Source: Social Security Administration). What percentage of full benefit does a person receive if that person retires at age 63? At what age will a retiree receive the full benefit? For what ages do you receive more than the full benefit?
160. Medicaid spending. The payment in billions by Medicaid (health care for the poor) can be modeled by the equation P = 12.6n + 81.3, where n is the number of years since 1990 (Health Care Financing Administration, www.hcfa.gov). a) What amount was paid out by Medicaid in 1995? b) In what year will the payment reach $220 billion? c) Graph the equation for n ranging from 0 through 20.
161.Women on the board. The percentage of companies with at least one woman on the board is growing steadily (Forbes, February 10, 1997). The percentage can be approximated with the linear equation p = 2n + 36, where n is the number of years since 1980. a) Find and interpret the pintercept for the line. b) Find and interpret the nintercept. c) Graph the line for n ranging from 0 through 20. d) If this trend continues, then in what year would you expect to find nearly all companies having at least one woman on the board?
162. Hazards of depth. The table on page 169 shows the depth below sea level and atmospheric pressure (Encyclopedia of Sports Science, 1997). The equation
A = 0.03d + 1 expresses the atmospheric pressure in terms of the depth d. a) Find the atmospheric pressure at the depth where nitrogen narcosis begins.
b) Find the maximum depth for intermediate divers. c) Graph the equation for d ranging from 0 to 250 feet.
163. Demand equation. Helen’s Health Foods usually sells 400 cans of ProPac Muscle Punch per week when the price is $5 per can. After experimenting with prices for some time, Helen has determined that the weekly demand can be found by using the equation d = 600 – 40p, where d is the number of cans and p is the price per can. a) Will Helen sell more or less Muscle Punch if she raises her price from $5? b) What happens to her sales every time she raises her price by $1? c) Graph the equation. d) What is the maximum price that she can charge and still sell at least one can?
164. Advertising blitz. Furniture City in Toronto had $24,000 to spend on advertising a yearend clearance sale. A 30second radio ad costs $300, and a 30second local television ad costs $400. To model this situation, the advertising manager wrote the equation 300x +400y = 24,000. What do x and y represent? Graph the equation. How many solutions are there to the equation, given that the number of ads of each type must be a whole number?
165. Material allocation. Atent maker had 4500 square yards of nylon tent material available. It takes 45 square yards of nylon to make an 8 ´ 10 tent and 50 square yards to make a 9 ´ 12 tent. To model this situation, the manager wrote the equation 45x + 50y = 4500. What do x and y represent? Graph the equation. How many solutions are there to the equation, given that the number of tents of each type must be a whole number?
166. Super cost. The average cost of a 30second ad during the 1995 super bowl was $1 million, and in 1998 it was $1.3 million (Detroit Free Press, January 6, 1998, www.freep.com). a) Find the slope of the line through (95, 1,000,000) and (98, 1,300,000) and interpret your result. b) Use the accompanying graph to estimate the average cost of an ad in 1997. c) What do you think the average cost will be in 2005?
167. Retirement pay. The annual Social Security benefit of a retiree depends on the age at the time of retirement. The accompanying graph gives the annual benefit for persons retiring at ages 62 through 70 in the year 2005 or later (Source: Social Security Administration). What is the annual benefit for a person who retires at age 64? At what retirement age does a person receive an annual benefit of $11,600? Find the slope of each line segment on the graph, and interpret your results. Why do people who postpone retirement until 70 years of age get the highest benefit?
168. Increasing training. The accompanying graph shows the percentage of U.S. workers receiving training by their employers. The percentage went from 5% in 1981 to 16% in 1995. Find the slope of this line. Interpret your result.
169. Saving for retirement. Financial advisors at Fidelity Investments, Boston, use the accompanying table as a measure of whether a client is on the road to a comfortable retirement. a) Graph these points and draw a line through them. b) What is the slope of the line? c) By what percentage of your salary should you be increasing your savings every year?
170. Write an equation in slopeintercept form, if possible, for each line. See Example 6. In each case, make a sketch. The line through (0, 6) that is perpendicular to the line y = 3x – 5
171. The line through (0, –1) that is perpendicular to the line y = x
172. The line with yintercept (0, 3) that is parallel to the line 2x + y = 5
173. The line through the origin that is parallel to the line 2x – 5y = 8
174. The line through (2, 3) that runs parallel to the xaxis
175. The line through (–3, 5) that runs parallel to the yaxis
176. The line through (0, 4) and (5, 0)
177. Marginal cost. A manufacturer plans to spend $150,000 on research and development for a new lawn mower and then $200 to manufacture each mower. The formula C = 200n + 150,000 gives the cost in dollars of n mowers. What is the cost of 5000 mowers? What is the cost of 5001 mowers? By how much did the one extra lawn mower increase the cost? (The increase in cost is called the marginal cost of the 5001st lawn mower.)
178. Marginal revenue. A defense attorney charges her client $4000 plus $120 per hour. The formula R = 120n + 4000 gives her revenue in dollars for n hours of work. What is her revenue for 100 hours of work? What is her revenue for 101 hours of work? By how much did the one extra hour of work increase the revenue? (The increase in revenue is called the marginal revenue for the 101st hour.)
179. Inhouse training. The accompanying graph shows the percentage of U.S. workers receiving training by their employers. The percentage went from 5% in year 0 (1981) to 16% in year 14 (1995). a) Find the slope of this line. b) Write the equation of the line in slopeintercept form. c) Use your equation to predict the percentage that will be receiving training in the year 2000.
180.

Women and marriage. The percentage of women in the 20 to 24 age group who have never married went from 64% in year 0 (1970) to 33% in year 26 (1996) (Census Bureau, www.census.gov). a) Find the equation of the line through the two points (0, 0.64) and (26, 0.33) in slopeintercept form.
b) Use your equation to predict what the percentage will be in the year 2000.
181. Pansies and snapdragons. A nursery manager plans to spend $100 on 6packs of pansies at 50 cents per pack and snapdragons at 25 cents per pack. The equation 0.50x + 0.25y = 100 can be used to model this situation. a) What do x and y represent? b) Graph the equation. c) Write the equation in slopeintercept form. d) What is the slope of the line? e) What does the slope tell you?
182. Pens and pencils. A bookstore manager plans to spend $60 on pens at 30 cents each and pencils at 10 cents each. The equation 0.10x + 0.30y = 60 can be used to model this situation. a) What do x and y represent? b) Graph the equation. c) Write the equation in slopeintercept form. d) What is the slope of the line? e) What does the slope tell you?
183. Find the equation of each line. Write each answer in standard form using only integers. See Example 2. The line through the points (1, 2) and (5, 8)
184. The line through the points (3, 5) and (8, 15)
185. The line through the points (–2, –1) and (3, –4)
Find the equation of each line. Write each answer in slopeintercept form. See Examples 3 and 4.
186. The line contains the point (3, 4) and is perpendicular to y = 3x – 1.
187. The line contains the point (–2, 3) and is perpendicular to y = 2x + 7.
188. The line is parallel to y = x – 9 and goes through the point (7, 10).
189. The line is perpendicular to 3x – 2y = 10 and passes through the point (1, 1).
190. The line is parallel to 2x + y = 8 and contains the point (–1, –3).
191. The line goes through (–1, 2) and is perpendicular to 3x + y = 5.
192. Automated tellers. ATM volume reached 10.6 billion transactions in 1996 (Electronic Commerce Data Base). The accompanying graph shows the steady growth of automatic tellers. a) Write the equation of the line through (92, 7.0) and (96, 10.6). b) Use the equation to predict the number of transactions at automated teller machines in the year 2005?
193. Direct deposit. In 1994, onethird of all workers participated in direct deposit of their paychecks and this number is expected to reach threefourths by the year 2000. (New York Automated Clearing House, www.nyach.org). a) Write the equation of the line through (1993, 1/3) and (2000, 3/4). b) Use the accompanying graph to predict the year in which 100% of all workers will participate in direct deposit of their paychecks. c) Use the equation from part (a) to predict the year in which 100% of all workers will participate in direct deposit of their paychecks.
194. Gross domestic product. The U.S. per capita gross domestic product went from $14,000 in 1970 to $18,000 in 1992 (World Resources, 1997). a) Write the equation of the line through the points (1970, 14,000) and (1992, 18,000). b) What do x and y represent in your equation? c) Graph the equation
d) By how much is the gross domestic product increasing per year? e) Use your equation to predict the per capita gross domestic product in the year 2000.
195.Bodymass index. The body mass index BMI is used to assess the level of fat in a person’s body. When Tim weighed 147 pounds his BMI was 23.4. When his weight went to 185, his BMI was 29.5. a) Find the equation of the line through (147, 23.4) and (185, 29.5). b) What do x and y represent in your equation?
c) Graph the equation. d) Interpret the slope of this line. e) What is his BMI when his weight is 160?
196.Profit per share. In the 1980s, People’s Gas had a profit per share, P, that was determined by the equation P = 0.35x + 4.60, where x ranges from 0 to 9 corresponding to the years 1980 to 1989. What was the profit per share in 1987? Sketch the graph of this formula for x ranging from 0 to 9.
197. Loan value of a car. For the first 6 years the loan value of a $30,000 Corvette is determined by the formula V = –4000a + 30,000, where a is the age in years of the Corvette. What is the loan value of this automobile when it is 5 years old? Sketch the graph of this formula for a between 0 and 6 inclusive.
198. Plumbing problems. When Millie called Pete’s Plumbing, Pete worked 2 hours and charged her $70. When her neighbor Rosalee called Pete, he worked 4 hours and charged her $110. Pete’s charge is a linear function of the number of hours he works. Find a formula for this function. How much will Pete charge for working 7 hours at Fred’s house?
199. Interior angles. The sum of the measures of the interior angles of a triangle is 180°.The sum of the measures of the interior angles of a square is 360°.The sum S of the measures of the interior angles of any nsided polygon is a linear function of the number of sides n. Express S as a linear function of n. What is the sum of the measures of the interior angles of an octagon?
200. If the shoe fits. If a child’s foot is 7.75 inches long, then the child wears a size 13 shoe. If the child has a foot that is 5.75 inches long, then the child wears a size 7 shoe. The shoe size S is a linear function of the length of the foot L. a) Write a linear equation expressing S as a function of L. b) What size shoe fits a child with a 6.25inch foot?
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