Question

3 bells ring at the time intervals of 25 minutes, 55 minutes and 45 minutes. At what time will the bells ring together?
1. 28 hours
2. 41.25 hours  
3. 30 hours
4. 11.75 hours
5. 25.5 hours

Answer 1

Correct Answer - Option 2 : 41.25 hours  

Concept Used:

Time when bells ring together is lcm of individual timings of the bells.

Calculations:

Time after which first bell rang = 25 mins

Time after which second bell rang = 55 mins

Time after which third bell rang = 45 mins

Time when all bells will ring together again = LCM of (25, 55, 45)

⇒ Time when all bells will ring together again =2475 mins = 2475/60 hours      [1 min = 1/60 hours]

⇒ Time when all bells will ring together again = 41.25 hours      

∴ The bells will ring together again after 41 hours 25 seconds.