5 bells start commencing together at 9 AM. They ring at intervals of 12 seconds, 18 seconds, 24 seconds, 36 seconds, and 45 seconds. At what time do the bells ring together again?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is Option 2 i.e. 9:06 AM.
Given that,
5 bells start commencing together at 9 AM
They ring at intervals of 12 seconds, 18 seconds, 24 seconds, 36 seconds, and 45 seconds
LCM of (12, 18, 24, 36, 48)
⇒ 12 = 2 × 2 × 3
⇒ 18 = 2 × 3 × 3
⇒ 24 = 2 × 2 × 2 × 3
⇒ 36 = 2 × 2 × 3 × 3
⇒ 45 = 3 × 3 × 5
LCM = 360 seconds = 6 min
Hence, the bells ring together again at 9:06 AM