Question

A train took 51 seconds to cross eight equally spaced posts and 10 seconds to cross a man standing still. What is the ratio of the distance between the adjacent post to the length of the train?
1. 41 : 70
2. 70 : 41
3. 51 : 80
4. 80 : 51

Answer 1

Correct Answer - Option 1 : 41 : 70

Calculation:

Let k be the distance between the adjacent post and p is the length of the train.

⇒ 7k + p = 51v      ----(I)

p = 10v

⇒ 7k = 51v - 10v = 41v

⇒ k/p = (41/7)/10 = 41/70

∴ The ratio is 41 : 70.

If there are n equally spaced posts with d distance between adjacent posts,

The total distance will be (n - 1)d.