• A tap can fill an empty tank in 12 h and a leakage can empty the tank in 20 h. If tap and leakage both work together, then how long will it take to fill the tank?

    A) 25 h

      B) 40 h

    C) 30 h

      D) 35 h

    Correct Answer:
    C) 30 h

    Description for Correct answer
    Part filled by tap in 1 h =\( \Large \frac{1}{12} \)

    Part emptied by leak in 1 h = \( \Large \frac{1}{20} \)

    Net part filled in 1 h when both (tap and leakage) work

    = \( \Large \frac{1}{12} \)-\( \Large \frac{1}{20} \)=\( \Large \frac{5-3}{60} \)=\( \Large \frac{2}{60} \)=\( \Large \frac{1}{30} \)

    Therefore, Required time to fill the tank = 30 h

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