Civil Service Exam Reviewer · Basic Operations · hard

Two school bells ring every 5 and 25 minutes, respectively. If they ring together at 8:00 AM, when will they next ring together?

1. 10:05 AM
2. 8:25 AM
3. 8:30 AM
4. 8:05 AM

Answer

B. 8:25 AM

Solution

They ring together every LCM(5, 25) = 25 minutes, so next at 8:25 AM.

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