Posted by **Jessica** on Sunday, July 8, 2012 at 12:29pm.

A sphere has a surface area of 28.26 in2. Find the diameter in inches, of the sphere. Use PI

Question 2

What is the surface area, in square inches, of a sphere with radius 3.5 in.? Use Pi and round your answer to the nearest hundredth, if necessary.

Question 3

Whats is the volume of a sphere with a radius of 18 cm?

LAST QUESTION

What is the volume of a sphere with a diameter of 23 in.?

Round to the nearest tenth.

A 1807.5

B.1982.4

C.2103.6

D.2027.8

- MAth -
**Steve**, Sunday, July 8, 2012 at 1:36pm
1. a = 4pi*r^2

28.26 = 4*3.14*r^2

r = 3/2, so diameter = 3

2. use above formula

3. v = 4/3 pi r^3 = 4/3 * 3.14 * 18^3 = 24416.64

4. use above formula. To estimate, 4/3 * pi is about 4. 4*11.5^3 = 6083. Hmmm. Nothing close. (?)

- MAth -
**Bosnian**, Sunday, July 8, 2012 at 1:37pm
A = 4 pi r ^ 2

A = 28.26

28.26 = 4 pi r ^ 2

28.26 / ( 4 pi ) = r ^ 2

r ^ 2 = 28.26 / ( 4 * 3.14 )

r ^ 2 = 28.26 / 12.56 = 2.25

r = sqrt ( 2.25 ) = 1.5 in

Question 2

A = 4 pi r ^ 2

A = 4 * pi * 3.5 ^ 2

A = 4 * 3.14 * 12.25

A = 153.86 in ^ 2

Question 3

V = 4 * pi * r ^ 3 / 3

V = 4 * 3.14 * 18 ^ 3 / 3

V = 4 * 3.14 * 5832 / 3

V = 73249.92 / 3

V = 24416.64 in ^ 3

LAST QUESTION

V = 4 * pi * r ^ 3 / 3

V = 4 * 3.14 * 23 ^ 3 / 3

V = 4 * 3.14 * 12167 / 3

V = 152817.52 / 3

V = 50939.1733 in ^ 3

V = 50939.2 in ^ 3

rounded to the nearest tenth

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