4 [The volume of a sphere is 4/3πr^3 ] (a) A spoon used for measuring in cookery consists of a hemispherical bowl and a handle. The internal volume of the hemispherical bowl is 20 cm^3. The handle is of length 5 cm. (i) Find the internal radius of the hemispherical bowl. (ii) The hemispherical bowl of a geometrically similar spoon has an internal volume of 50 cm^3. Find the length of its handle. (b) [The surface area of a sphere is 4πr^2] An open hemisphere of radius 5.5 cm is used to make a metal kitchen strainer. 50 holes are cut out of the curved surface. Assume that the piece of metal removed to make each hole is a circle of radius 1.5 mm. Calculate the external surface area that remains.