Time and Distance – Trains

1. A 300 metre long train crosses a platform in 39 seconds while it crosses a signal pole in 18 seconds. What is the length of the platform?
   A.310 m
   B.350 m
   C.600 m
   D.490 m
   E.None of these
   
   Answer

   Answer – B (350 m)
   Explanation – when it cross a pole actually it is crossing itself
   so, S = 300/18
   let length of platform be “p”
   relative speed = total lengths/time
   speed of train = [300 + p ]/39
   (300/18)x39=300 +p
   650 -300=p
   p=350 m
   Note : in this type of question one thing is pole,man and other is of considerable length like platform ,bridge.
   when train crosses pole,man it crosses itself

2.Two trains running in opposite directions cross a man standing on the platform in 27 seconds and 17 seconds respectively and they cross each other in 23 seconds. The ratio of their speeds is:
A.1 : 3
B.3 : 4
C.3 : 2
D.Data inadequate
E.None of these

Answer

Answer – C (3 : 2)
Explanation – Let the speeds of the two trains be x m/sec and y m/sec respectively.
Then, length of the first train = 27x metres,
and length of the second train = 17y metres.
relative speed = total lengths/time
y – x = [27x + 17 y ]/23
23y -23x = 27x + 17 y
27x+23x= 23 y-17y
4x=6y
x/y=6/4=3/2= 3:2

3.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. 1: 2
B. 4 : 3
C. 7 : 8
D. 3 : 4
E. none of these

Answer

Answer- B (4:3)
Explanation:
Let us name the trains as A and B. Then,
trick formula
(A’s speed) : (B’s speed) = square root of b : square-root of a =square-root of 16 : square-root of 9 = 4 : 3.

Time and Distance – Trains

1. Two trains are moving in opposite directions at 60 km/hr and 90 km/hr. Their lengths are 1.10 km and 0.9 km respectively. The time taken by the slower train to cross the faster train in seconds is:
58 sec 50 sec 48 sec 56 sec


A 270 m long train running at the speed of 120 kmph crosses another train running in opposite direction at the speed of 80 kmph in 9 seconds. What is the length of the other train?
180 230 245 235


Two trains of equal length are running on parallel lines in the same direction at 46 km/hr and 36 km/hr. The faster train passes the slower train in 36 seconds. The length of each train is:
40 50 65 55


A train 125 m long passes a man, running at 5 kmph in the same direction in which the train is going, in 10 seconds. The speed of the train is:
35 km/hr 55 km/hr 48 km/hr 50 km/hr


A train travelling at a speed of 75 mph enters a tunnel 7/2 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?
1 min 3 min 5 min 6 min