If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

# Using related volumes

Use related volumes (using the volume of one figure to determine the volume of another). Created by Sal Khan.

## Want to join the conversation?

• I have a question about the last figure E. What is the meaning of by a scale factor of 1.5? I thought it should be 1.5 times the base area, not the side length.
• I got that wrong too. Dilation/Scale Factor is by scaling its coordinates or lengths.
• Can someone please explain how Sal solved for the volume of Figure E?
I am very confused!
Thanks in advance and have a BLESSED day!
• Sorry for a late response, but if you are still wondering, since E's base is a scale of A's base of 2.25 or 1.5^2 (he shows in the video by multiplying each side of the base by 1.5), he then has 2.25b times h because they have the same heights. He multiplies 2.25 by 28 because b and h are the dimensions of figure A, and the volume of figure A was given.
Hope this helps if you see this!
• When is 1.5x² equal to 1.5²x²?
• Those are never equal. The exponent is only on the "x" in the version on the left. If you start with (1.5x)², then it is equal to 1.5²x² because the exponent applies to both values.
Hope this helps.
• Is a cylinder a prism?
• Yes, you can think of a cylinder as a circular prism.
• The easiest numbers to calculate would be x=2 and h=7. And the last figure would have a volume of 63 fyi.
• how do you find the height of a pentagonal prism? I can't find it I looked everywhere