cylindrical artificial

[yorkmanz]

A city park contains a cylindrical artificial pond that has a radius of 7.5m.
A 2m concrete deck will be constructed around the pond. The concrete should be at least 15 cm thick.
Calculate the minimum volume of concrete required to construct the deck, to one decimal place?


help please?

 

[LCKurtz]

Do you know the formula for the volume of a right circular cylinder? And what if a cylindrical hole is removed from it?