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Home Aptitude Pipes and Cistern See What Others Are Saying!
  • Question
  • A cistern has three pipes A, B and C. Pipes A and B can fill it in 3 and 4 h, respectively, while pipe C can empty the completely filled cistern in 1 h. If the pipes are opened in order at 3:00 pm, 4:00 pm and 5:00 pm, respectively , at what time will the cistern be empty?


  • Options
  • A. 6:15 pm
  • B. 7:12 pm
  • C. 8:12 pm
  • D. 8:35 pm

  • Correct Answer
  • 7:12 pm 

    Explanation

    Let the cistern gets emptied in m h after 3:pm
    Work done by A in m h, by B in (m - 1) h and by c in (m - 2) h= 0
    ? m/3 + (m - 1)/4 - (m - 2) = 0
    ? 4m + 3(m - 1) - 12(m - 2) = 0
    ? 5m = 21
    ? m = 21/5 = 4.2
    ? m = 4 h 12 min
    ? Required time = 7 : 12 pm.


  • More questions

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      In a race of 600 m, A can beat B by 60 m and in a race of 500 m, B can beat C by 50 m. By how many meter will A beat C in a race of 400 m?

    • Options
    • A. 78 m
    • B. 56 m
    • C. 76 m
    • D. 86 m
    • Discuss
    • 2. 
      0.15 / (0.5 / 15) =?

    • Options
    • A. 4.5
    • B. 45
    • C. 0.03
    • D. 0.45
    • Discuss
    • 3. 
      For any integers a and b with HCF (a, b) = 1, what is HCF (a + b, a - b) equal to?

    • Options
    • A. It is always 1
    • B. It is always 2
    • C. Either 1 or 2
    • D. None of the above
    • Discuss
    • 4. 5358 x 51 =?

    • Options
    • A. 273258
    • B. 273268
    • C. 273348
    • D. 273358
    • Discuss
    • 5. Which of the following numbers is divisible by each one of 3, 7, 9 and 11?

    • Options
    • A. 639
    • B. 2079
    • C. 3791
    • D. 37911
    • E. None of these
    • Discuss
    • 6. 
      If the total sales for a business in a certain year were ? 132000. What were the sales in june, if june sales were half the monthly average?

    • Options
    • A. ? 8400
    • B. ? 7200
    • C. ? 5500
    • D. ? 6300
    • Discuss
    • 7. 
      If 0.8 x A = 0.09 x B, then find A : B.

    • Options
    • A. 9 : 80
    • B. 3 : 80
    • C. 80 : 9
    • D. 7 : 80
    • Discuss
    • 8. 
      A 4% stock yield 5%. The market value of the stock is?

    • Options
    • A. Rs. 125
    • B. Rs. 80
    • C. Rs. 99
    • D. Rs. 109
    • Discuss
    • 9. 
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    • Options
    • A. 7.44673
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    • Discuss
    • 10. 
      Maganlal, a worker, makes an article in every 2/3h. If he works for 7 1/ 2h, then how many articles will he make?

    • Options
    • A. 111/4
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    • C. 112/6
    • D. 112/5
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