A grain silo is composed of a cylinder topped with a hemisphere. The diameter of the silo is 12m, and the height of the entire structure 32m. Calculate how many cans of paint are needed to paint the building if each can of paint can cover 42m^2.
This is where sketches come in handy. If you can sketch in 3D then I suggest doing so but make sure you know how to distinguish between the side of the silo and the cap. A simple line circling the division between the two should work. You can also draw a simple 2D sketch, again drawing the division bewteen the side and the cap of the silo. What is a hemishpere? We commonly see the use of the word hemishpere when referring to the Earth. It is the division of a circle into two equal parts. With the Earth, the division occurs at the equator or along any of the meridians of the Earth but most commonly the meridian diving the Earth into the Western and Eastern hemispheres. So you have half a sphere at the top of the silo. Figure out the area of the outer part of the silo and add it to the area covered by the hemisphere at the top of the silo. You should be able to find the formulae for area of both a cylinder and a hemisphere (or half of a sphere or a ball). Take you total area and divide it by the area covered by one can of paint.
