There are three persons M,N And P. They are running in the same direction around a circular track of length 150 m. Their speeds are 20 m/sec,15 m/sec and 12 m/sec, respectively. If they start at same time and same point, then after what time do they meet for the first time?

Correct option is C

Given:

Length of circular track = 150 m

Speeds of M = 20 m/s, N = 15 m/s, P = 12 m/s

All start together from the same point and run in the same direction

Concept Used:

When moving in the same direction, time to meet again at the starting point is the LCM of the times each takes to complete one round.

Formula Used:

Time to complete 1 round = $$\frac{\text{Track length}}{\text{Speed}}$$​​

Solution:

Time taken to complete one round:

M: $$\frac{150}{20}$$ = 7.5 sec

N: $$\frac{150}{15}$$​ = 10 sec

P: $$\frac{150}{12}$$ = 12.5 sec

LCM of 7.5, 10, and 12.5 = 150 

Thus, time they meet again at starting point is 150 sec.