Six bells commence tolling together and toll at intervals of 2, 4, 6, 8, 10 and 12 seconds respectively. In 30 minutes , how many times do they toll together ?

A. 4

B. 10

C. 15

D. 16

Answer: Option D

Solution(By Examveda Team)

LCM of 2, 4, 6, 8, 10, 12 is 120
So the bells will toll together after every 120 seconds, i.e., 2 minutes
In 30 minutes, they will toll together
$$\eqalign{ & = \left[ {\left( {\frac{{30}}{2}} \right) + 1} \right] \cr & = {\text{16 times}} \cr} $$