Question

Six different bells in a tower toll at the
intervals of 9 sec, 12 sec, 15 sec, 18 sec,
21 sec and 24 sec respectively. If all of
them toll at 6 am, the next time they toll
together is:​

Answer 1

Answer:

Since all are to toll together next, this interval has to be the L.C.M.of 12, 15, 20, 25 and 45 which is 900 seconds or 15 minutes.

∴ Time when all five bells will toll together next is 5.15 am.

Thus the answer is (c).