Correct Answer - Option 3 : 79.2 kmph
Given:
Length of the bridge = 264 m.
Time taken to crosses the bridge = 20 sec.
Time taken to crosses the post = 8 sec.
Formula used:
Speed = Distance covered/ime taken
Calculation:
Let length of the train = y m
To crosses the bridge train need to cover = Train's length + Bridge length = (y + 264)
Now, Speed of train is same in both case
⇒ y/8 = (264 + y)/20
⇒ 20y = 264 × 8 + 8y
⇒ 20y - y = 264 × 8
⇒ 12y = 264 × 8
⇒ y = (264 × 8)/12
⇒ y =176 m.
Length of the train = 176 m
Speed of the train = 176/8 = 22 m/sec = (22 × 18)/5 = 79.2 Kmph
∴ The Speed of the train is 79.2 kmph
