If the ratio of the radii of two spheres is 6 : 5, what is the ratio of the surface areas of the two spheres?

6 : 5

6r2ππ : 5r2ππ

36 : 25

216 : 125

Answer: Choice C) 36:25

To get this answer, we simply square each piece of the original ratio 6:5

6^2 = 36

5^2 = 25

Think of two squares where one has a side length of 6 and the other of 5. The ratio of the sides is 6:5. The areas of the two squares are 36 and 25 as mentioned above. So the ratio is 36:25. This idea can be applied to any surface area or area in general. It doesn't have to be two squares. The reason why we can apply this to any general shape is because we can break up the shape into small squares to get a rough approximation. The more squares we use, the better the approximation.