A can run 4 times as fast as B and gives B a start of 63 m. How long should the race course be so that A and B might reach in the same time?	Choose the correct answer:
A) 70 m	B) 60 m	C) 80 m	D) 65 m	E) 84 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 63 m he gains 63 * ( 4 / 3 ) i . e 84 m answer : e"
Answer: E