Six bells commence tolling together and toll at the intervals of 2, 4, 6, 8, 10 and 12 seconds respectively. In the first 10 minutes, how many times would they have tolled together?

Correct option is D

Given:

Tolling intervals of bells = 2, 4, 6, 8, 10, 12 seconds
Total duration = 10 minutes = 600 seconds

Solution:

LCM (2 , 4, 6, 8, 10 ,12) = 120 seconds

In 600 seconds, number of times they toll together:

​$$\frac{600}{120} +$$​1 = 5 + 1 = 6 times