Question

6. three bells toll at intervals 9,12, 15 minutes respectively. if they start tolling together, after what time will they toll together again

Answer 1

Hi,

This problem based on the concept

of LCM.

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 .

I hope this will useful to you.

****

Answer 2

Three bells toll at intervals - 9min , 12 min and 15min.

So , if they start tolling together, they will ring together at LCM ( 9,12,15)

So, We have to find LCM of 9 , 12 and 15.

9 = 3×3

12 = 2×2×3

15 = 3×5

LCM (9, 12,15) = 3×3×2×2×5 = 180

So , the LCM of 9 , 12 and 15 is 180. The bells will toll together after 180 minutes or 3 hours.

Answer) Bells will toll together after 180 minutes or 3 hours.