Question

Q26. There are five bells which start ringing together at intervals of 3, 6, 9, 12 and 15 seconds respectively. In 39 minutes, how many times will the bell ring simultaneously?

• A. (a) 13
• B. (b) 6
• C. (c) 12
• D. (d) 5

Answer 1

The correct option is A

(a) 13

LCM of 3, 6, 9, 12, 15

So bells ring after every 180 seconds i.e., 3 min

So in 3 min bell will ring at 0 sec. as well

So bells will ring 1 + 12 = 13 times

LCM = 180