Approximately how many revolutions will be made by a car tire with a 15-inch diameter if the car ...
Approximately how many revolutions will be made by a car tire with a 15-inch diameter if the car travels 1⁄2 mile?
Answer/Solution
669
Steps/Work
Diameter of car tire = 15 inches
Radius of car tire = 7.5 inches = 7.5*2.54 cm = 19.05 cm
Circumference of the car tire = 2*pi * 19.05 = 2 *3.14 *19.05= 119.63 cm
Distance traveled by car = .5 mile = .5 *1.6 km = .8 km = 800 m = 8 * 10^4 cm
Number of revolutions =Distance traveled / Circumference of tire = 8 * 10^4 / 119.63 = 668.73
Since the answer choices are far apart we should use estimation in this question .
Ideally ,in the GMAT the conversion between units would be provided .
Answer A
Radius of car tire = 7.5 inches = 7.5*2.54 cm = 19.05 cm
Circumference of the car tire = 2*pi * 19.05 = 2 *3.14 *19.05= 119.63 cm
Distance traveled by car = .5 mile = .5 *1.6 km = .8 km = 800 m = 8 * 10^4 cm
Number of revolutions =Distance traveled / Circumference of tire = 8 * 10^4 / 119.63 = 668.73
Since the answer choices are far apart we should use estimation in this question .
Ideally ,in the GMAT the conversion between units would be provided .
Answer A