Three bells start ringing after interval of 20 minutes, 25 minutes and 40 minutes. They ringsimultaneously at 8: 00 am. They will ring simultaneously again at :

Correct option is C

Given:

Three bells ring at intervals of 20 minutes, 25 minutes, and 40 minutes.

They ring together at 8:00 AM. Find the time when they will ring together again.

Solution:

20 = $$2^2 \times$$​ 5

25 = $$5^2$$​​

40 = $$2^3 \times 5$$​​

LCM = $$2^3 \times 5^2 = 8 \times 25$$​ = 200 minutes

200 minutes = 3 hours 20 minutes

Now,  They will rang together at; 

= 8:00 AM + 3:20 = 11:20 AM