AMC8 1992

AMC8 1992 · Q12

AMC8 1992 · Q12. It mainly tests Averages (mean).

The five tires of a car (four road tires and a full-sized spare) were rotated so that each tire was used the same number of miles during the first 30,000 miles the car traveled. For how many miles were each tire used?

一辆车的五个轮胎（四个公路轮胎和一个全尺寸备用胎）在汽车行驶的前30,000英里中进行了轮换，使得每个轮胎的使用里程相同。每个轮胎使用了多少英里？

(A) 6000 6000

(B) 7500 7500

(D) 30,000 30,000

(E) 37,500 37,500

Answer

Correct choice: (C)

正确答案：（C）

Solution

Answer (C): The total number of miles of wear is 30,000 × 4 = 120,000. Since the wear is shared equally by each of the 5 tires, each tire traveled 120,000÷5 = 24,000 miles. OR Since each of the tires was on for \[ \frac{4}{5} \] of the driving, it follows that each was used \[ \frac{4}{5} \times 30,000 = 24,000 \] miles.

答案 (C)：总磨损里程为30,000 × 4 = 120,000。由5个轮胎均等分担，每轮胎行驶120,000÷5 = 24,000英里。或者每个轮胎使用时间占驾驶时间的 \[ \frac{4}{5} \]，因此每个轮胎使用 \[ \frac{4}{5} \times 30,000 = 24,000 \] 英里。

Topics

AR.006 Averages (mean)