The given figure shows a solid cylinder of height h cm and radius r cm. If the slant height of the conical cavity is l cm, the total surface area of the remaining solid is :

1. πrl + 2πrh + 2πr²

2. πr² + πrl + 2πrh

3. 2πr² - πrl + 2πrh

4. (πrl + πr²) + 2πr² + 2πrh

In the given figure, a solid cone is kept inverted in a closed cylindrical container such that the height of cone = height of cylinder = h, radius of cone = radius of cylinder = r and slant height of cone = l. If the remaining of cylinder is completely filled with water, the wetted surface area of the whole body is :

1. 2πrh + πr² + πrl

2. 2πrh + πrl

3. 2πrh + 2πr² + πrl

4. 2πrh - πr² + πrl

A cone of height 15 cm and diameter 7 cm is mounted on a hemisphere of same diameter. Determine the volume of the solid thus formed.

A buoy is made in the form of a hemisphere surmounted by a right cone whose circular base coincides with the plane surface of the hemisphere. The radius of the base of the cone is 3.5 metres and its volume is two-third of the hemisphere. Calculate the height of the cone and the surface area of the buoy, correct to two places of decimal.