A train overtakes two persons walking along a railway track. The first one walks at 4.5 km/hr. The other one walks at 5.4 km/hr. The train needs 8.4 and 8.5 seconds respectively to overtake them. What is the speed of the train if both the persons are walking in the same direction as the train?
Answers
Answered by
14
4.5 km/hr =
4.5 x
5/18
m/sec = 1.25 m/sec
5.4 km/hr = 5.4 x 5/18 m/sec = 1.5 m/sec
Relative speed of the train to the first person = x - 1.25
Relative speed of the train to the second person = x - 1.5
Now,(x - 1.25) x 8.4 = (x - 1.5) x 8.5
=> 8.4x - 10.5 = 8.5x - 12.75
=>0.1x = 2.25
=>x = 22.5
=>Speed of the train = 22.5 x (5/18) = 81km/hr
5.4 km/hr = 5.4 x 5/18 m/sec = 1.5 m/sec
Relative speed of the train to the first person = x - 1.25
Relative speed of the train to the second person = x - 1.5
Now,(x - 1.25) x 8.4 = (x - 1.5) x 8.5
=> 8.4x - 10.5 = 8.5x - 12.75
=>0.1x = 2.25
=>x = 22.5
=>Speed of the train = 22.5 x (5/18) = 81km/hr
Similar questions