Try to calculate the volume of the soil so dug out .

Put the values of the radius and height in the formula.

Start with calculating the height of the cylidrical tank first by relating it with the given total surface area .

Put all the given values in the formula and then try to work out the solution using inverse operation .

First find out the area covered in one revolution.

First find out the value of radius and then find the curved surface area and total surface area .

Find the volume of hollow part and external part first and then take away.

Find the volume of cream first.

What would be the height and radius of the cylindrical tank so formed ?

Use the formula and calculate the value of total surface area .