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
Monday, November 26, 2007
QUESTION # 5
Posted by Gaurav & Kunal at 9:55 PM
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3 Comments:
Answer is 12 m/s
Got late on answering, but if I'll still put the explanation if it is helpful to someone.
From the 2 races, the data that we gather is that B is beaten by 6 sec in first run and B beats A by 2 sec in second race.
Hence a time difference of 8 sec is observed and A's speed is constant.
Thus, the 8 seconds are used by B to cover the distance 144-48 i.e. 96 m. (The only term that changes in both cases)
Hence, B's speed is 96/8 = 12 m/s.
both of you are counted in... and have 1 point each for this answer
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