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April 18, 2014

April 18, 2014

Posted by **melinda** on Thursday, January 12, 2012 at 10:05pm.

Thanky ou!

Find the ratio of the surface area of a cylinder to the volume of the cylinder if the height remains at 10 cm. Simplify this ratio and let f(x) = the simplified ratio. Let r be the radius of the cylinder.

a) Find the average rate of change as the radius increases from 2 to 5 cm.

b) Is the ratio increasing of decreasing? justify answer based on part a.

- Precalculus -
**Damon**, Thursday, January 12, 2012 at 10:15pmIt is not clear if the surface area includes the top and bottom. I will assume not

then

area = 2 pi r h

volume = pi r^2 h

ratio = 2 /r

well that is too easy, try including top and bottom

area = 2 pi r h + 2 pi r^2

volume = pi r^2 h

ratio = 2/r + 2/h

= 2/r + .2 if h = 10

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