Question

If one bell rings every 5 seconds and the other one rings every 10 seconds starting from 0 seconds, then they will ring together after seconds.

• A. 10
• B. 5
• C. 15

Answer 1

The correct option is A 10

Multiples of 5 = 5, 10, 15, 20, ...
Multiples of 10 = 10, 20, 30, 40, ...

The bells will ring together at the seconds which are multiples of both 5 and 10.

So starting from 0, the two bells will ring together at 10th second or after 10 seconds.