New SAT Math Workbook

The more people working the less time it will take

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Unformatted text preview: ple working, the less time it will take. The fewer people working, the longer it will take. The product of the number of people and the time worked remains constant. E) How long food, or any commodity, lasts varies inversely as the number of people who consume it. The more people, the less time it will last. The fewer people, the longer it will last. The product of the number of people and the time it will last remains constant. Example: If 3 men can paint a house in 2 days, how long will it take 2 men to do the same job? Solution: The fewer men, the more days. This is inverse. 3⋅ 2 = 2 ⋅ x 6 = 2x x = 3 days www.petersons.com 60 Chapter 4 Exercise 3 Work out each problem. Circle the letter that appears before your answer. 1. A field can be plowed by 8 machines in 6 hours. If 3 machines are broken and cannot be used, how many hours will it take to plow the field? (A) 12 (B) (C) (D) (E) 2. 3 5 3 3 4 4. Two boys weighing 60 pounds and 80 pounds balance a seesaw. How many feet from the fulcrum must the heavier boy sit if the lighter boy is 8 feet from the fulcrum? (A) 10 (B) (C) (D) (E) 10 3 9 7 2 6 1 2 9 4 16 Camp Starlight has enough milk to feed 90 children for 4 days. If 10 of the children do not drink milk, how many days will the supply last? (A) 5 (B) 6 (C) (D) (E) 4 1 2 1 4 8 1 5 3 5. A gear with 20 teeth revolving at 200 revolutions per minute is meshed with a second gear turning at 250 revolutions per minute. How many teeth does this gear have? (A) 16 (B) 25 (C) 15 (D) 10 (E) 24 3. A pulley revolving at 200 revolutions per minute has a diameter of 15 inches. It is belted to a second pulley which revolves at 150 revolutions per minute. Find the diameter, in inches, of the second pulley. (A) 11.2 (B) 20 (C) 18 (D) 16.4 (E) 2 www.petersons.com Variation 61 In solving variation problems, you must decide whether the two quantities involved change in the same direction, in which case it is direct variation and should be solved by means of proportions. If the quantities chang...
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