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    Question

    Pipe A can empty a completely filled tank in 40 hours.

    Pipe B and A together can fill an empty tank completely in (z+4) hours. The efficiency of pipe B is 60% more than the efficiency of pipe C. Pipe B and C together can fill the empty tank together in 20 hours. Find out the value of ‘z’.(Calculate values approximately)
    A 169 Correct Answer Incorrect Answer
    B 120 Correct Answer Incorrect Answer
    C 100 Correct Answer Incorrect Answer
    D 195 Correct Answer Incorrect Answer
    E none of these Correct Answer Incorrect Answer

    Solution

    ATQ, Let’s assume the capacity of the tank is 480 units. Efficiency of Pipe A = 480 / 40 = -12 units/hour. The efficiency of pipe B is 60% more than the efficiency of pipe C. Let’s assume the efficiency of pipe C is ‘2c’. Efficiency of pipe B = 2c of (100+60)% = 2c of 160% = 3.2c Pipe B and C together can fill the empty tank together in 20 hours. (3.2c + 2c) x 20 = 480 5.2c = 24 c = 480 / 104 c = 4.615 (approx) Pipe B and A together can fill an empty tank completely in (z+4) hours. (3.2c - 12) x (z+4) = 480 (3.2x4.615 - 12) x (z+4) = 480 (14.768 - 12) x (z+4) = 480 2.768 x (z+4) = 480 (z+4) ≈ 480 / 2.768 z ≈ 173.12 - 4 z ≈ 169.12 Value of ‘z’ ≈ 169.12. or 169

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