1992 AMC 8 Problem 12

Below is the professionally curated solution for Problem 12 of the 1992 AMC 8, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 1992 AMC 8 solutions, or check the answer key.

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Concepts:rate

Difficulty rating: 980

12.

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 30,00030{,}000 miles the car traveled. For how many miles was each tire used?

60006000

75007500

24,00024{,}000

30,00030{,}000

37,50037{,}500

Solution:

During the 30,00030{,}000 miles, 44 tires are always in use, so the total tire-mileage is 4×30,000=120,0004 \times 30{,}000 = 120{,}000 tire-miles.

Split equally among 55 tires, each tire is used 120,0005=24,000\dfrac{120{,}000}{5} = 24{,}000 miles.

Thus, the correct answer is C .

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