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Question

A train crosses a pole and a bridge of length 140 meters in 3 seconds and 10 seconds respectively. At what speed the train is running?

  • 62
  • 66
  • 72
  • 76
Answer- C

Let the length of the train is X meters and its speed Y m/s

Time=Distance/Speed

X/Y = 3, X=3Y.....(1)

(X+140)/Y = 10, X=10Y-140......(2)

from equation (1) to equation (2)

3Y=10Y-140

7Y=140Y=20 m/s

Y= 20x18/5 = 72km/hr