a2zinterviews

21.	Two trains, one from Howrah to Patna and the other from Patna to Howrah, start simultaneously. After they meet, the trains reach their destinations after 9 hours and 16 hours respectively The ratio of their speeds is
	A.  2 : 3
	B.  4 : 3
	C.  6 : 7
	D.  9 : 16

Solution

Let us name the trains as A and B. = (A'S speed) : (B's speed) =√b : √a = √16 : √9 = 4 : 3

22.	Two trains 100 meters and 120 meters long aer running in the same diredtion with speeds of 72 km/hr and 54 km/hr. In how much time will the first train cross the seconds?
	A.  40 sec
	B.  44 sec
	C.  46 sec
	D.  48 sec

Solution

Relative Speed of trains = (72 - 54) km/hr = 18 km/hr = (18 x 5 /18) km/hr = 5 m /sec. Time taken to cover = (100 + 120) m/sec = (220 / 5 ) sec = 44 sec

23.	A train 220 m long is running with a speed of 59 kmph. In what time will it pass a man who is running at 7 kmph in the direction opposite to that in which the train is going?
	A.  12 sec
	B.   15 sec
	C.  16 sec
	D.  18 sec

Solution

Speed of the train = (59 + 7) kmph = (66 x 5 /18) m/sec = (55 / 3) m/sec. Time taken by it cover 220m at (55/3) m/sec = (220 x 3/55) sec = 12 sec.

24.	A train 360 m long is running at a speed of 45 km/hr. In what time it will it pass a bridge 140 m long?
	A.  40 sec
	B.  42 sec
	C.  45 sec
	D.  48 sec

Solution

speed =(45 + 5 / 18)m/sec =(25 / 2)m/sec Total distance covered =(360 + 140 )m =500 m Required time =(500 x 2 / 25)sec = 40 sec.

25.	A train covers a distance of 12 km in 10 minutes. If it takes 6 seconds to pass a telegraph post, then the length of the train is
	A.  90 m
	B.  100 m
	C.  120 m
	D.  140 m

Solution

Speed = (12 / 10 x 60)km/hr = (72 x 5/18) m/sec = 20 m/sec. Length of the train = (speed x time ) = (20 x 6)m = 120 m.