A 180 meter long train crosses a man standing on the platform in 6 sec. What is the speed of the train?
Options:
(A) 229
(B) 108
(C) 278
(D) 126
(E) 112
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S = 180/6 * 18/5 = 108 kmph So the answer is: (B).
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A train 210 m long, running with a speed of 63 km/hr will pass a tree in?
Options:
(A) 15 sec
(B) 16 sec
(C) 18 sec
(D) 12 sec
(E) 25 sec
--
Speed = 63 * 5/18 = 35/2 m/sec
Time taken = 210 * 2/35 = 12 sec So the answer is: (D).
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Two pipes A and B can fill a cistern in 20 and 30 minutes respectively, and a third pipe C can empty it in 40 minutes. How long will it take to fill the cistern if all the three are opened at the same time?
Options:
(A) 19 1/7 min
(B) 15 1/7 min
(C) 17 1/7 min
(D) 7 1/7 min
(E) 7 2/7 min
--
1/20 + 1/30 - 1/40 = 7/120
120/7 = 17 1/7 So the answer is: (C).
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