Question
A train crosses a 300-metre-long bridge in 20 seconds,
and the same train crosses a tunnel twice the length of the bridge in 35 seconds. Find the speed of train in km/h.Solution
Let the length and speed of train be ‘l’ metres and ‘x’ m/s, respectively.
Then, according to question,
(l + 300)/20 = (l + 600)/35
7l + 2100 = 4l + 2400
3l = 300
l = 100 metres
x = (l + 300)/20 = 400/20 = 20 m/s = 20×(18/5) = 72 km/h
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