Advertisements

A train moves past a telegraph post and a bridge 264 m long in 8 seconds and 20 seconds respectively. What is the speed of the train?

A) 69.5 km/hr

B) 70 km/hr

C) 79 km/hr

D) 79.2 km/hr

Length of the Bridge = 264 m.

Time taken to pass the bridge = 20 sec.

Time taken to passe the post = 8 sec.

Length of the train = X m (Let.)

To pass the bridge train need to cover Train’s length + Bridge legnth  (X +264).

Speed = Distance covered / time taken

Now,

X/8 = (264 + X)/20

20X = 264 *8 + 8X

20X – X = 264 *8

12X = 264 *8

X = (264 *8)/12

X = 176 m.

Speed of the train = 176/8 = 22 m/sec = (22*18)/5 = 79.2 Kmph

Advertisements