the correct question is
A cylinder has a volume of 320 pi in³. and a height of 5". Find the radius of the cylinder
we know that
[volume of a cylinder]=pi*r²*h----> r²=volume/(pi*h)
r=√[volume/(pi*h)]
volume=320*pi in³
h=5 in
so
r=√[320*pi/(pi*5)]--------> r=8 in
the answer is
8 in