A train overtakes two persons who are walking in the same direction in which the train is going, at the rate of 2 kmph and 4 kmph and passes them completely in 9 and 10 seconds respectively. The length of the train is
Select the correct answer
Solution! 2 kmph = 2 * (5/18)m/s = 5/9 m/s
4 kmph = 4 * (5/18)m/s = 10/9 m/s
Let the length of the train be x metres and its speed by y m/sec.
then, x/[y - (5/9)] = 9 and x/[y - (10/9)] = 10
So, 9y - 5 = x and 10(9y - 10) = 9x
9y - x = 5 and 90y - 9x = 100
On solving, we get x = 50
Hence, Length of the train is 50 m..
Question No 21
A boatman goes 2 km against the current of the stream in 1 hour and goes 1 km along the current in 10 minutes. How long will it take to go 5 km in stationary water?