Which will have a greater effect on the volume of the prism: doubling the height or doubling the width? explain your reasons.

Doubling the width has a greater effect on volume.
The volume of a prism is calculated by this formula:
Prism Volume = Area of Base • Height
The Area of the Base is calculated by this formula:
area = n * side² / (4*tan(180 / # of sides)

So, we see that doubling the width (the side length) will increase the volume by 4 whereas doubling the height only doubles the volume.
 

The answer would be 13.5 minutes.