Pipes and Cisterns Practice Test 1 with solutions

Question : 3 of 40

Marks: +1, -0

Two pipes A and B can fill a tank in 3 hours and 7 hours respectively. If they are opened at alternate hours starting with A first, then, the time taken to fill the tank is:

$5 1/7$ hours
$4 1/7$ hours
$4 1/3$ hours
5 hours
None of these

Validate

Solution:

Part of cistern filled in 1 hour by Pipe A =

1/3

Part of cistern filled in 1 hour by Pipe B =

1/7

Part of cistern filled in 2 hours by A + B
=

1/3 + 1/7

{7+3}/{21}

{10}/{21}

Part of cistern filled in 4 hours by A and B
=

{10}/{21} × 2

{20}/{21}

Remaining part = 1 -

{20}/{21}

1/{21}

Pipe A can fill tank in 3 hours
Pipe A can fill

1/{21}

th part of the tank in

3/{21}

1/7

hours.
So, total time taken =

4 1/7

hours

Go to Question:

Prev Question

Next Question