A train 150m long passes a km stone in 15 seconds and another train of the same length travelling in opposite direction in 8 seconds. The speeds of the second train is:

First, find the speed of the first train by dividing its length of 150 meters by the 15 seconds it takes to pass a km stone, which gives 10 m/s. When passing the second train moving in the opposite direction, the total distance is 150 plus 150, or 300 meters, and the time is 8 seconds; using the relative speed formula, their combined speed is 300 divided by 8, or 37.5 m/s. Subtracting the first train's speed gives the second train's speed of 27.5 m/s. Converting this to kilometers per hour yields 27.5 multiplied by 18/5, which equals 99 kmph.

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