Tires problem
Algebra
Level
2
A truck driver buys 5 tires (4 plus a spare), each tire can be used for 40000 km before it has to be replaced. How far can the driver travel if he uses the 5 tires completely?
The answer is 50000.
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1 solution
Assuming that the tires can be changed with infinitesimal short period of time, then the 5 tires are used with an equal period of time. Since only 4 of the 5 tires are used at an instant, the period of time before the 5 tires are completely used is thus 4 0 0 0 0 × 4 5 = 5 0 0 0 0 km.