Calculate the radius of a given hemisphere?

Question

A solid hemisphere has a volume of 230cm^3.

Calculate the radius of the hemisphere.

Ok every time I try to do this question, something seems to go wrong. I use the formula for a sphere with radius r... V=4 over 3 times Pi times r². I divide this by 2 so I get 1 over 2 (4 over 3 times Pi times r²). I follow this through, substituting and rearranging as I go but nothing seems to work. Any assistance would be greatly appreciated.

Answer 1

(4/3)pi(r^3)

= volume of a sphere

volume of a hemisphere is 1/2 that or (2/3)pi(r^3) = 230

pi(r^3)/3 = 115

pi(r^3) = 345

r^3 = 345/pi = about 109.8

r = the cube root of 345/pi = (109.8)^1/3 = about 4.8 or slightly less than 4.8 cm radius