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

    Question

    P, Q and R together can complete a task in 12 days. Q and R

    together can finish it in (72/5) days, and R alone can do half the task in 8 days. What is the efficiency ratio of P to Q?
    A 4:5 Correct Answer Incorrect Answer
    B 2:1 Correct Answer Incorrect Answer
    C 1:3 Correct Answer Incorrect Answer
    D 3:7 Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    ATQ,

    1/P + 1/Q + 1/R = 1/12

    R alone completes the whole task = 8 * 2 = 16 days

    1/P = 1/12 – 5/72 = (6 – 5)/72 = 1/72

    1/Q = 5/72 – 1/16 = (10 – 9)/144 = 1/144

    P alone completes the task = 72 days

    Q alone completes the task = 144 days

    Required ratio = (1/72) : (1/144) = 2 : 1

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