A hemispherical tank full of water is being emptied by a pipe at the rate of 347 litres per second. How much time will it take to empty the tank if the diameter of the tank is 3 m?

Find the approximate volume and surface area of a sphere of radius 6 cm. (Use π = 227)

Ram has two spherical balls of radius 10.5 cm each and Meena has six spherical balls of radius 7 cm each. What is the total volume of the balls that Meena has?