# 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:

- 90 km/hr
- 75 km/hr
- 25 km/hr
- 125 km/hr

**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.