Question

three bells ring at intervals of 15 20 and 30 minutes.if they all ring at 12 noon together , at wha time will they ring together again

Answer 1

first we will have to take out the l.c.m of 15,20,30 which is 60 which means they will together in 60 minutes or 1 he .so after 12 noon they will ring together at 1 p.m

Answer 2

"Factorise the time of ringing

15 = 3 * 5

20 = 2 * 2 * 5

30 = 2 * 3 * 5

LCM = 5 * 3 * 2 * 2 = 60

Hence, the bell will again ring at the same time after 60 minutes. It rang at 12:00 noon and hence will ring at 1:00 pm again.

"