Question

Threes bells toll at interval of 12,18,20 minutes respectively if they start tolling together after what time will they next toll together

Answer 1

all three bell will rang together after 180 min or 3 hours

Answer 2

First bell toll after = 12 min

Second bell toll after = 18 min

Third bell toll after = 20 min

The next time that the three bells toll together is the LCM of 12,18,20

LCM :-

12 = 2 × 2 × 3

18 = 2 × 3 × 3

20 = 2 × 2 × 5

LCM = 2 × 2 × 3 × 3 × 5

LCM = 180

Therefore , the three bells toll after 180 min ( or ) 3 hours.