Question

A can of energy drink is a cylinder with the dimensions shown below. How much material is needed to make the can?

Answer 1

The answer would be 40cm

Answer 2

The question asks for the surface area of the can. First, we find the area of the two circles. Area is pi * r^2. The areas of each circle separately is 16 * pi, and the area of both circles combined is 32 * pi. Then, we find the area of the body of the cylinder. If we roll the cylinder out, we get a rectangle. The area of a rectangle is length * width. For the cylinder, we see that one side of the rectangle is the circumference of the circle, and the other side is the height of the cylinder. The formula for a circumference of a circle is 2 * pi * r. The circumference of the circle is 8 * pi. We know that the height is 10, so the area of the body of the cylinder is 80 * pi. Finally we add the area of the circles and the area of the body of the cylinder to get 80 * pi + 32 * pi = 112 * pi. 112 pi square cm if material are needed to make the can.