UPSC CDS Math Work, Time and Unitary Method Questions

Let the volume of the tank be V.Volume of tank filled by pipe X in 1 hour =

V

2

Volume of the tank filled by pipe Y in 1 hour =

V

6

Suppose the tank gets filled t hours after 11 a.m
∴

V

2

×t+

V

6

×t
=V−

V

2

=

V

2

⇒

t

2

+

t

6

=

1

2

⇒

4t

6

=

1

2

⇒t=

3

4

hours = 45 minutes
Thus, the tank will be filled at 11:45 a.m.