$\"\"$

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 $\"\"$ .