📢 Too many exams? Don’t know which one suits you best? Book Your Free Expert 👉 call Now!

    Question

    Three pipes A, B, and C can fill a tank in 50 minutes,

    60 minutes, and 75 minutes respectively. All are opened together. A is closed after 'n' minutes, and B is closed (2n - 6) minutes before the tank is filled. If the tank is filled in 40 minutes, find the value of 'n'.
    A 14 Correct Answer Incorrect Answer
    B 20 Correct Answer Incorrect Answer
    C 18 Correct Answer Incorrect Answer
    D 6 Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Let the total capacity of tank be 300 litres (LCM of 50, 60, 75)
    Efficiency of A = 300 ÷ 50 = 6 litres/minute
    Efficiency of B = 300 ÷ 60 = 5 litres/minute
    Efficiency of C = 300 ÷ 75 = 4 litres/minute So,
    (6 + 5 + 4) × n + (5 + 4) × (40 - n - (2n - 6)) + 4 × (2n - 6) = 300
    Or, 15n + 9(46 - 3n) + 8n - 24 = 300
    Or, 15n + 414 - 27n + 8n - 24 = 300
    Or, -4n + 390 = 300
    Or, n = 22.5 minutes

    Practice Next
    More Pipes and cisterns Questions

    Relevant for Exams:

    ask-question