# Problems on Trains - Aptitude Questions and Answers - RejinpaulPlacement

22.
The length of the bridge, which a train 130 metres long and travelling at 45 km/hr can cross in 30 seconds is: [Sections Officers 2001]

Solution:   Speed of the train
= (45 * (5/18)) m/sec
= (25/2) m/sec.

Time = 30 sec.

Let the length of bridge be x metres.

Then, (130 +x)/30 = 25/2
2(130 +x) = 750
x = 245 m.
23.
A train 800 metres long is running at a speed of 78 km/hr. If it crosses a tunnel in 1 minute, then the length of the tunnel (in metres) is: [S.S.C 2003]

Solution:   Speed of the train
= (78 * (5/18)) m/sec
= (65/3) m/sec.

Time = 1 minute = 60 sec.

Let the length of the tunnel be x metres.

Then, (800 + x) / 60 = 65/3
3(800 + x) = 3900
x = 500.
24.
A goods train run at the speed of 72 kmph and crosses a 250 m long platform in 26 seconds. What is the length of the goods train? [Bank P.O. 2003]

Solution:   Speed of the goods train = [72 * (5/18)] m/sec = 20 m/sec.

Time = 26 sec.

Let the length of the train be x metres.

Then, (x + 250) / 26 = 20
x + 250 = 520
x=270 m.
25.
The length of the train and that of a platform are equal. If with a speed of 90 km/hr, the train crosses the platform iin one minute, then the length of the train (in metres) is:

Solution:   Speed of the train = [90 * (5/18)] m/sec = 25 m/sec.

Time = 1 min = 60 sec.

Let the length of the train and that of the platform be x metres.

Then, 2x/60 = 25
x = (25 * 60) /2
x= 750.
26.
A train of length 150 metres takes 40.5 seconds to cross a tunnel of length 300 metres. What is the speed of the train in km/hr?

Solution:   Speed of the train = ((150 + 300) / 40.5) m/sec
= (450/40.5) * (18/5) km/hr
= 40 km/hr
27.
A train crosses a platform 100 m long in 60 seconds at a speed of 45 km/hr. The time taken by the train to cross an electric pole is:

Solution:   Speed of the train
= [45 * (5/18)] m/sec
= (25/2) m/sec.

Let the length of the train be x metres.

Then, (x + 100) / (25/2) =60 or x = 650 m

Time taken by the train to cross an electric pole = (650 * (2/25)) sec = 52 sec
28.
A train passes a station platform in 36 seconds and a man standing on the platform in 20 seconds. If the speed of the train is 54 km/hr, what is the length of the platform? [G.INDOMAT 1997]

Solution:   Speed of the train = (54 * (5/18)) m/sec = 15 m/sec.

Length of the train = (15 * 20) m = 300 m.

Let the length of the platform be x metres.

Then, (x + 300) / 36 = 15
=> x + 300 = 540
=> x= 240 m.