A can run 4 times as fast as B and gives B a start of 75 m. How long should the race course be so that A and B might reach in the same time? Choose the correct choice from the following options:
A) 70 m  B) 60 m  C) 100 m  D) 65 m  E) 75 m

Rationale: "speed of a : speed of b = 4 : 1 means in a race of 4 m a gains 3 m . then in a race of 75 m he gains 75 * ( 4 / 3 ) i . e 100 m answer : c"
Answer: C