4) The DIAMETER of a sphere is doubled. What is the new volume of the sphere?
A) 83πr3 B) 163πr3 C) 323πr3 D) 643

Question

4) 	The DIAMETER of a sphere is doubled. What is the new volume of the sphere?	
A)	83πr3 		B)	163πr3 		C)	323πr3 		D)	643

amistre64 · Answer

what is the usual formula for the volume of a sphere?

anonymous · Answer

We need the original volume or diameter.

anonymous · Answer

thats what im trying to see

amistre64 · Answer

dont need the original stuff; just let r = d/2 in the usual formula

then let d = 4d

amistre64 · Answer

pfft, d = 2d :)

amistre64 · Answer

so, since r = d/2,  and twice d is 2d

the new r is simply,  r = 2d/2 = d = (2r)

amistre64 · Answer

i recall the r being cubed in the usual format soo,  (2r)^3 = ?

anonymous · Answer

the answer is b

amistre64 · Answer

i do not believe it is b, what is your reasoning?

anonymous · Answer

sa=4pi r2 
=4pi(2r)^2 
4pi time 4r2 
16pi r2

amistre64 · Answer

volume is not surface area

anonymous · Answer

its easy we lookin for the surface area

anonymous · Answer

not volume

amistre64 · Answer

your surface area equation is rather nice tho :)  but we should do that for volume of a sphere ... then your post was incorrect when it asked for volume?

amistre64 · Answer

all you options have an r^3 in them as well