MBApyq

Two-way Pipes Tank Filling

XAT 2017 · Quantitative Ability & Data Interpretation · Medium · Quantitative Ability

All XAT 2017 questionsMore Quantitative Ability questionsAll XAT QADI

Four two-way pipes A, B, C and D can either fill an empty tank or drain the full tank in 4, 10, 12 and 20 minutes respectively. All four pipes were opened simultaneously when the tank is empty. Under which of the following conditions the tank would be half filled after 30 minutes?

  1. A.

    Pipe A filled and pipes B, C and D drained

  2. B.

    Pipe A drained and pipes B, C and D filled

  3. C.

    Pipes A and D drained and pipes B and C filled

  4. D.

    Pipes A and D filled and pipes B and C drained

  5. E.

    None of the above

Answer

A

Explanation

Let the total capacity of the tank be LCM(4,10,12,20)=60\text{LCM}(4, 10, 12, 20) = 60 units. Rate of A =60/4=15= 60/4 = 15 units/min. Rate of B =60/10=6= 60/10 = 6 units/min. Rate of C =60/12=5= 60/12 = 5 units/min. Rate of D =60/20=3= 60/20 = 3 units/min.

We want the tank to be half-filled (30 units) in 30 minutes, so net filling rate =30/30=1= 30/30 = 1 unit/min.

Testing option A: Pipe A filling, B, C, D draining: Net rate =+15−6−5−3=+1= +15 - 6 - 5 - 3 = +1 unit/min. This satisfies the condition.

Related Quantitative Ability questions

Practise this under exam conditions

Sign in to solve it with a live timer, the on-screen CAT calculator, and streak and accuracy tracking across every question you attempt.

Solve in the workspace