The volume is the amount of stuff that a container can hold on the inside, while the surface area is the amount of stuff that goes on the outside of the container (eg: the amount of paint or wallpaper). In the case of wallpapering a room, we're actually doing the inner walls rather than the outside walls; however, it's the same concept. The surface area only deals with the surface and we want to find out how much area we have to cover. That way we can know how much wallpaper to buy. For problem 1, he needs to know the volume so he can find out how much trash each can would be able to hold. The greater the volume, the larger the bin. For instance a small wastebasket would have a small volume compared to a large waist high heavy duty trash container.
