Sunday, August 15, 2010

GMAT Question of the day

A and B ran a race of 480 m. In the first heat, A gives B a head start of 48 m and beats him by 1/10th of a minute. In the second heat, A gives B a head start
of 144 m and is beaten by 1/30th of a minute. What is B’s speed in m/s?
(A) 12
(B) 14
(C) 16
(D) 18
(E) 20

Race 1 :
ta = tb-6 ( because A beats B by 6 sec)
Race 2 :
Ta = tb+2 ( because A looses to B by 2 sec)

We know D= S * T

480/Sa = 432/Sb -6
480/Sa = 336/Sb +2

Equating these two equations we get Sb = 12

ta,Sa stand for time taken by A and speed of A resp