New Enroll in RBI Grade B New Batch - Starts on May 21

    Question

    Pipe L can fill a pool in 30 hours and pipe M in 45

    hours. If both the pipes are opened in an empty pool, how much time will they take to fill it?
    A 24 hours Correct Answer Incorrect Answer
    B 17 hours Correct Answer Incorrect Answer
    C 18 hours Correct Answer Incorrect Answer
    D 20 hours Correct Answer Incorrect Answer

    Solution

    Pipe L fills the pool in 30 hours, so its rate is {1/30} per hour. Pipe M fills it in 45 hours, so its rate is {1/45} per hour. Together, their rate is {1/30} + {1/45} = {3/90} + {2/90} = {5/90} = {1/18}. So, both pipes together will fill the pool in 18 hours.

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