Victory for the ACT Student Text 15e

214 • M ATH

PERCENTAGES

38. If the population of a town was 20,000 in 1997 and 16,000 in 2007, what was the ’‡”…‡– †‡…Ž‹‡ ‹ –Š‡ –‘™ǯ• ’‘’—Žƒ–‹‘ǫ F. 50% G. 25% H. 20% J. 10% K. 5% Items #39–41 refer to the following table. CAPITOL CITY FIRES Year Number of Fires 2002 100 2003 125 2004 140 2005 150 2006 135 39. Š‡ —„‡” ‘ˆ ϐ‹”‡• ‹ ʹͲͲʹ ™ƒ• ™Šƒ– ’‡”…‡–ƒ‰‡ ‘ˆ –Š‡ —„‡” ‘ˆ ϐ‹”‡• ‹ ʹͲͲ͵ǫ A. 25% B. %66 3 2 C. 80% D. 100% E. 125% 40. Š‡ —„‡” ‘ˆ ϐ‹”‡• ‹ ʹͲͲ͸ ™ƒ• ™Šƒ– ’‡”…‡–ƒ‰‡ ‘ˆ –Š‡ —„‡” ‘ˆ ϐ‹”‡• ‹ ʹͲͲͷǫ F. 90% G. 82% H. 50% J. 25% K. 10%

35. A jar contains 24 white marbles and 48 black marbles. What percentage of the marbles in the jar are black? A. 10% B. 25% C. %33 3 1 D. 60% E. %66 3 2 36. A group of three friends shared the cost of a tape recorder. If Andy, Barbara, and Donna each paid $12, $30, and $18, respectively, then Donna paid what percentage of the cost of the tape recorder? F. 10% G. 30% H. %33 3 1 J. 50% K. %66 3 2 Twenty students attended Professor ‘†”‹‰—‡œǯ•…Žƒ•• ‘ ‘†ƒ› ƒ† 25 students attended on Tuesday. The number of students who attended on Tuesday was what percentage of the number of students who attended on Monday? A. 5% B. 20% C. 25% D. 80% E. 125% Class What about percentages greater –Šƒ ͳͲͲǫ ‡–ǯ• consider an example. If the number of students on Thursday is 150% of the number of students on Wednesday, then the number of students on Thursday is equal to the number of students on Wednesday plus 50% of the number of students on Wednesday. In other words, 150% is the same as multiplying by 1.5. Throwback to Math Class ‘ ϐ‹† ’‡”…‡–ƒ‰‡…Šƒ‰‡ǡ ’—– –Š‡…Šƒ‰‡ ‹ –Š‡ “—ƒ–‹–› ‘˜‡” –Š‡ original amount. Multiply this fraction by 100 to change the fraction to a percentage. % 100 Original Amount New Amount Original Amount Change − = ] g 37. The Cambridge Edge Percentage problems can be summarized as “ a is x percent of b ,” or, less formally, “this is some percentage of that.” To solve these problems, create a fraction with b or “of that” as the denominator and a or “this is” as the numerator. Set this fraction equal to the percentage over 100. Cross-multiply to solve for the unknown. % 100 of is Throwback to Math

What was the percent decrease in the —„‡” ‘ˆ ϐ‹”‡• ˆ”‘ ʹͲͲͷ –‘ ʹͲͲ͸ǫ A. 10% B. 25% C. 50% D. 82% E. 90%

41.