The work done is calculated by :.

(a).

Since we have to calculate the work done to fill the tank to a depth of the value ranges

from  to .

.

Apply integration :

(b).

Since we have to calculate the work done to fill the tank to a depth of to a depth of

the value ranges from to .

.

Apply integration :

(a).

The work done to fill the tank to a depth of is or .

(b).

The work done to fill the tank to a depth of to a depth of is or \ \

.