a container opened at the top and made of a metal sheet is the form of a frustum of a cone of height 16 cm with radii of its lower and upper ends as 8 and 20 CM respectively find the cost of milk which can completely filled the container at the rate of rupees 50 litres also find the cost of metal sheet used to make container if the cost rupees 10 per centimetre square (take Pi 3.14)​