The speed of the second train is:

A train 150 m long passes a km stone in 30 seconds and another train of the same length travelling opposite direction in 10 direction in 10 seconds. The speed of the second train is:

  1. 90 km/hr
  2. 75 km/hr
  3. 25 km/hr
  4. 125 km/hr
Anurag Mishra Professor Asked on 11th December 2015 in Maths.
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1 Answer(s)

Answer:  (1) 90 km/hr

Explanation:-
Let the speed of the another train = X m/sec
The length of a train = 150 m
Time taken by the train = 30 sec
Then, the speed of a train = 150/30
 = 5 m/sec

Relative speed = (X + 5 ) m/sec 
Then, (150 + 150)/(X + 5) = 10
300 = 10 X + 50
10 X = 300 – 50
X = 250/10
X = 25 m/sec
The speed in km/hr = 25 x 18/5
 = 90 km/hr

Then, the speed of another train is 90 km/hr.

Hence, the answer is (1) 90 km/hr. 

Anurag Mishra Professor Answered on 11th December 2015.
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