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?

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

A cylindrical water tank has a radius of 2.8 m and a height of 3.5 m. If an average person needs 70 liters of water per day, for how many people will the water in the fully filled tank suffice for one day? (Take π = 227)