4 bells ring at intervals of 6, 8, 9 and 10 seconds. All the bells ring at the same time. After how many minutes will they ring together again?

Correct option is D

Given:

- Four bells ring at intervals of 6, 8, 9, and 10 seconds.
- We need to find after how many minutes they will ring together again.
Concept Used:
To find when all the bells will ring together again, we need to calculate the Least Common Multiple (LCM) of their intervals.
Prime Factorizations:
- 6 = $$2 \times 3$$​​
- 8 = $$2^3$$​​
- 9 = $$3^2$$​​
- 10 = $$2 \times 5$$​​
The LCM is the product of the highest powers of all prime factors:
​$$LCM = 2^3 \times 3^2 \times 5 = 360$$​​
So, the bells will ring together again after 360 seconds.
​$$360 \div 60 = 6 \text{ minutes}$$​​
The bells will ring together again after 6 minutes.