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Railways PYQCBT 1 2016

RRB NTPC · Question 8

Three clocks are designed to alarm in every hour, two hours and three hours respectively. If they all alarmed together three hours before, then after how many hours from now will they next alarm together? A. 3 hours B. 6 hours C. 2 hours D. 1 hours

  1. D

  2. A

  3. B

  4. C

Show answer & explanation

Answer: (B) A

Explanation

The clocks ring together every LCM(1, 2, 3) = 6 hours. They rang together 3 hours ago, so they will ring together again 6 − 3 = 3 hours from now.