Question

Four bells ring in the intervels of 5,10,15 and 20 mts if they ring together at 9:00 am then at what time they will again ring together.?

A)10:00
B)10:30
C)11:00
​

Answer 1

Take LCM of 5,10,15,20

That is 60

Hence after 60 min they will ring

That's at 10:00

Hope it helps you