six bells commence tolling together at 7:59 am. They toll at intervals of 3,6,9,12 and 15 seconds respectively. How many time will they toll together till 8:17 am? (excluding the toll at 7:59 am)
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 6
First we need to find the LCM of 3, 6, 9, 12 and 15 to know after what time they will ring together again
LCM is 15 x 4 x 3 = 180 seconds
Hence now we know that after 180 seconds or after 3 minutes they will ring together again
Total minutes between 8:17 am and 7:59 am = 18 minutes
In 15 minutes they will ring = = 6 times