A hollow spherical shell is made of a metal of density 3 g/cm3. Its internal and external radii are 15 cm and 18 cm, respectively. What is the weight (in kg) of the shell? (Take π = 227)

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?