NIACL Model Paper 8 with solutions for free online practice

(1) Part of tank filled by thepipe in 1 hour =

1

10

Due to leak the pipe has to work extra 2 hours to fill the tank.
∴Part of tank filled by thepipe in 2 hours =

2

10

=

1

5

Now

1

5

th of the tank is emptied by the leak in 12 hours.
∴ The completely filled tank will get emptied in 12×5=60 hours.
Aliter : Using direct formula,
Required time =

10×12

12−10

= 60 hours
Aliter :

1

10

−

1

t

=

1

12

⇒

1

t

=

1

10

−

1

12

=

6−5

60

=

1

60

∴t = 60 hours