Question

One bell rings at an interval of every 10 minutes and a second bell rings at an interval of every 12 minutes how many minutes must go by for the bells to ring at the same time? How many times would you hear them ringing at the same time if 240 minutes went by?

Answer 1

Find the Least Common Multiple (LCM) of 10 and 12

10 = 2 x 5

12 = 2 x 2 x 3

LCM = 2 (5 x 2 x 3) = 60

Answer: 60 minutes, which occurs 4 times in 240 minutes