Suface Area of Sphere and volum

• Jan 11th 2009, 02:52 AM
Diligent_Learner
Suface Area of Sphere and volum
Can you Explain to me this question :

The volume, V, and surface area, S of a sphere with radius r are given by the formulas

http://www12.0zz0.com/2009/01/11/11/734672347.jpg

Find the surface area of a sphere that has a volume = 321 cm3. (To 2 decimal places)

Find the volume of the sphere that has surface area = 400 cm2 .To 2 decimal places)
• Jan 11th 2009, 03:06 AM
Moo
Hello,
Quote:

Originally Posted by Diligent_Learner
Can you Explain to me this question :

The volume, V, and surface area, S of a sphere with radius r are given by the formulas

http://www12.0zz0.com/2009/01/11/11/734672347.jpg

Find the surface area of a sphere that has a volume = 321 cm3. (To 2 decimal places)

Find the volume of the sphere that has surface area = 400 cm2 .To 2 decimal places)

For the first one :
You have $\displaystyle V=\frac 43 \pi r^3=321$
And you want $\displaystyle S=4 \pi r^2$
From the volume formula, you have :
$\displaystyle r^3=\frac{321 \cdot 3}{4 \pi}$
Hence $\displaystyle r=\sqrt[3]{\frac{321 \cdot 3}{4 \pi}}$

And substitute in the formula for S.

It's the exact same reasoning for the second one.
• Jan 15th 2009, 11:36 AM
Diligent_Learner
Thank you very much for cooperation..

I solve the question and I obtain the following results:

S=226.98

V=179.41