Question

Three bell toll at intervals of 9 ,12,15 minutes respectively. If they start tolling together , after what time will they next toll together

Answer 1

Here we have to find LCM of intervals

9 , 12 , 15 minutes which indicates

after how long they all again toll

together.

Write 9 , 12 and 15 product of prime

factors,

9 = 3 × 3

12 = 2 × 2 × 3

15 = 3 × 5

LCM( 9 , 12 , 15 ) = 3 × 3 × 2 × 2 × 5

= 180

Three bell toll together after 180

minutes .

Answer 2

Answer:

Given that three bells toll at intervals of 9,12,15 minutes.

Prime factorization of 9 = 3 * 3

Prime factorization of 12 = 2 * 2 * 3

Prime factorization of 15 = 3 * 5

LCM(9,12,15) = 3 * 3 * 2 * 2 * 5

                    = 180.

Therefore the bells will ring together after 180 minutes (or) 3 hours.

Hope this helps!