Pipes and Cisterns Practice Test 1 with solutions

Question : 13 of 40

Marks: +1, -0

Two pipes A and B can fill a water tank in 20 and 24 minutes respectively and third pipe C can empty at the rate of 3 gallons per minute. If A, B and C opened together filled the tank in 15 minutes, the capacity (in gallons) of the tank is:

Validate

Solution:

In 1 minute the part emptied by pipe C =

(1/{20}+1/{24}) - 1/{15}

{11}/{120}-1/{15}

3/{120}

1/{40}

Hence, pipe C can empty the tank in 40 minutes.
Therefore, capacity of the tank = 40 × 3 = 120 gallons.

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