Question

Four bells commence tolling together and then toll at intervals of 6, 7, 8 and 9 seconds respectively. After how many seconds do all the bells ring together?

• A. 504
• B. 516
• C. 508
• D. 512

Answer 1

The correct option is A 504

We know that bell 1 tolls after every 6 seconds, bell 2 after 7 seconds and so on. To find after how many seconds do the bells toll together, we need to find the LCM of the given numbers.
$\therefore$ L.C.M = 2 $\times$ 3 $\times$ 7 $\times$ 4 $\times$ 3 = 504
These bells toll together after 504 seconds.