GMAT Math Practice - Speed Time Races

Concept: Basic concept of races. Relative speed.

This GMAT Math practice question is from the topic rates: Concept covered is race between two runners.

Question: A runs 25% faster than B and is able to give him a start of 7 meters to end a race in dead heat. What is the length of the race?

  1. 10 meters
  2. 25 meters
  3. 45 meters
  4. 15 meters
  5. 35 meters

Explanatory Answer

Video explanation will be added soon

A runs 25% as fast as B.
i.e., if B runs 100 m in a given time, A will run 125 m in the same time.
In other words, if A runs 5 m in a given time, then B will run 4 m in the same time.

Therefore, if the length of a race is 5 m, then A can give B a start of 1 m (A can allow B to start 1 ahead of the starting point) so that they finish the race in a dead heat.
Ratio of length of start given : length of race :: 1 : 5

In this question, we know that the start given is 7 m.
Hence, the length of the race will be 7 * 5 = 35 m.

Choice E is the correct answer.

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