Question : Three bells ring at intervals of 36 seconds, 40 seconds, and 48 seconds, respectively. They start ringing together at a particular time. They will ring together after every:
Option 1: 6 minutes
Option 2: 12 minutes
Option 3: 18 minutes
Option 4: 24 minutes
Correct Answer: 12 minutes
Solution :
36 = 3 × 3 × 2 × 2
40 = 2 × 2 × 2 × 5
48 = 2 × 2 × 2 × 2 × 3
So, LCM = 2 × 2 × 2 × 2 × 3 × 3 × 5 = 720
After 720 seconds, all bells ring simultaneously.
Therefore, on converting seconds into minutes, we get $\frac{720}{60}$ = 12 minutes
Hence, the correct answer is 12 minutes.
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