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    Three bells start ringing after interval of 20 minutes, 25 minutes and 40 minutes. They ring simultaneously at 8:00 am. They will ring simultaneously
    Question

    Three bells start ringing after interval of 20 minutes, 25 minutes and 40 minutes. They ring simultaneously at 8:00 am. They will ring simultaneously again at

    A.

    9:00 am

    B.

    10:00 am

    C.

    11:20 am

    D.

    12:20 pm

    Correct option is C

    Given:

    Three bells ring at intervals of 20 minutes, 25 minutes, and 40 minutes.

    They ring together at 8:00 AM. Find the next time they will ring simultaneously.

    Solution:

    Prime factorization:

    20 = 22×52^2 \times 5​​

    25 = 525^2​​

    40 = 23×5 2^3 \times 5​​

    LCM = 23×52=8×25 2^3 \times 5^2 = 8 \times 25​ = 200 minutes

    Convert 200 minutes:

    200 = 3 hours 20 minutes

    Add to given time:

    8:00 AM + 3:20 = 11:20 AM

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