Management Aptitude Test Sep 2013 Paper

(c) Let the common ratio be x.
Since, pipe A takes 2x h to fill or to empty the tank.
Pipe B takes 3x h to fill or to empty the tank.
Pipe C takes 4x h to fill or to empty the tank.
Now, Pipe A and B can fill the tank in 3 h
∴ =

1

2x

+

1

3x

=

1

3

=

3+2

6x

=

1

3

x =

5×3

6

=

5

2

So, pipe A, B and C simultaneously take 5h, 7.5 h and 10 h to fill or to empty the tank.
Now, by given condition,
(

1

5

+

1

7.5

−

1

10

) + (

1

7.5

+

1

10

−

1

5

) + (

1

10

+

1

5

−

1

7.5

)
= (

6+4−3

30

) + (

4+3−6

30

) + (

3+6−4

30

)
=

7

30

+

1

30

+

5

30

=

13

30

=

2

5

Hence, after 3 h tank is

2

5

filled