In problem 12, to get the ratio of side lengths from the ratio of volumes, you need to CUBE root (not square root) the ratio of volumes:
[tex] \sqrt[3]{ \frac{64}{125} } = \frac{4}{5} [/tex]
So the ratio of Pyramid S to Pyramid T side lengths is 4:5.
To get surface area, you can then square this ratio...so 16:25
In 13, you need to take similar steps.
The ratio of heights is 24:36, which reduces to 2:3. To get the ratio of areas, you need to square the ratio of heights to get 4:9. This is the answer to 13a.
Your answer to 13b is correct (it's the cube of the ratio of lengths).
Let me know if you need any further clarification.
