Question

a train 150 m long is running at a speed of 72km/h.it crosses a bridge in 13 sec.find the length of the bridge

Answer 1

length =x
ATQ. 150+x is distance
(150+x)*18/5=13
150+x=65/18
x=65/18-150

Answer 2

let the length of bridge to be x meter.

distance=150+x, distance=20 m

time= 1 3 sec, time= 1 sec.

its a direct variation
150+x/13=20/1
150+x=260
x=110m is the real answer