# RRB NTPC - Problems on Trains

11.

How much time does a train 110 metres long running at the speed of 72 km/hr take to cross a bridge 132 metres in length?

A.) 14.3 seconds
B.) 12.1 seconds
C.) 9.8 seconds
D.) 12.42 seconds

Given, Length of train = 110 meter
Speed of train =72 km/hr
Length of bridge =132 metre
---> Converting Speed from km/hr into m/sec
=>Speed of train = 72 × (5/18) m/sec
= 4 × 5
20 m/sec
Formula:-Time taken by train to cross the bridge = (Length of the train + Length of the bridge) /Speed of train
= (110 + 132) / 20
= 242/ 20
= 12.1 sec
Thus,Time taken by train to cross the bridge =12.1 seconds

12.

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?

A.) 120 m
B.) 240 m
C.) 300 m
D.) 250 m

Given,speed of the train = 54 km/hr
---> converting this speed into meter/ sec
=> Speed of the train = (54 x 5 / 18 ) m/sec = 15 m/sec
Given that, thetrain passesa man in 20 seconds.
=> Length of the train = speed of the train × Time to pass theman
= 15 × 20
300 meter
Given that, thetrain passesa platform in 36 seconds.
=> Length of the train + Length of the platform = speed of the train × Time to pass the platform
=> 300 +Length of the platform = 15 × 36
=>Length of the platform = 540 - 300
=>Length of the platform = 240 meter.

13.

A train travelling at a speed of 75 mph enters a tunnel 3 (1/2) miles long. The train is 1/4 mile long. How long does it take for the train to pass through the tunnel from the moment the front enters to the moment the rear emerges?

A.) 2.5 min
B.) 3 min
C.) 3.2 min
D.) 3.5 min

Total distance covered = ( 7/2 + 1/4 ) miles
= 15/4 miles.
Therefore, Time taken
= ( 15 / 4 x 75 ) hrs
= 1 / 20 hrs
= ( 1/20 x 60 ) min.
= 3 min.

14.

Two trains are running at 60 Kmph and 42 Kmph respectively, in same direction. Fast train completely passes a man sitting in the slower train in 30sec. what is the length of the faster train?

A.) 100m
B.) 125m
C.) 150m
D.) 175m

L = S × T
L = 18 × 5/18 × 30
(in same direction Speed = first train - second train)
= 150m

15.

A train 240 m long passes a pole in 24 seconds. How long will it take to pass a platform 650 m long?

A.) 65 sec
B.) 89 sec
C.) 100 sec
D.) 150 sec

Given, length of the train = 240 m
Time taken by the train to pass the pole = 24 sec
Length of the Platform = 650 m
To find theTime taken by the train to pass the platform:-
Speed of the train = length of the train /Time taken by the train to pass the pole
= (240/ 24 )
= 10 m/sec.
Therefore, Time taken by the train to pass the platform = (length of the train + Length of the Platform) / Speed of the train
= [(240 + 650) / 10] sec
89 sec