39. If a spherical ball is enlarged so that its surface area is 9 times greater than its original surface area, then the original radius was multiplied by _________.

Question

39.   If a spherical ball is enlarged so that its surface area is 9 times greater than its original surface area, then the original radius was multiplied by _________.

anonymous · Answer

What is the formula for a sphere's surface area?

anonymous · Answer

4 x pi x r^2

anonymous · Answer

You mean 4 x pi x r^2 = a
(I forget the letter that is used to represent surface area)
anyway, if the area is 9 times as large then you get 9a.
Solve for a

anonymous · Answer

I'm confused...

anonymous · Answer

All formula's have two sides. Since we know that the the area is 9 times as large we can multiply the area by 9, with me so far?

anonymous · Answer

don't just give them the answer, that's worse then not helping at all.

anonymous · Answer

No, these are practice problems I found on my own to study. It is very helpful. Thanks!

anonymous · Answer

4πr^2 = S
4π(x*r)^2 = 9S

Keep going with it :)

anonymous · Answer

If you are trying to understand the problem, your understanding will not be improved by getting the answer given to you, or even just an equation, true understanding is being able to do the whole thing on your own.

anonymous · Answer

Ivory is right ;) My fault for giving it away so quickly