In a 10 km race, A, B and C each run at uniform speed, get the first, second and third position respectively. If A beats B by 1 km and B beats C by 1 km, then, by how much distance A beat C?
In a 10 km race, A, B and C each run at uniform speed, get the first, second and third position respectively. If A beats B by 1 km and B beats C by 1 km, then, by how much distance A beat C?
Solution
When A finishes the 10 km race, B has completed 9 km (A beats B by 1 km).
When B finishes the 10 km race, C has completed 9 km (B beats C by 1 km).
Since they run at uniform speeds, the speed ratio equals the distance ratio when time is the same.
When A completes 10 km, B completes 9 km in the same time.
Speed ratio of A to B:
When B completes 10 km, C completes 9 km in the same time.
Speed ratio of B to C:
To combine the ratios and :
When A covers 100 units, C covers 81 units.
When A covers 10 km, C covers:
km
Distance by which A beats C:
km
Therefore, A beats C by 1.9 km.
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