SOLUTION: The weight of a sphere is proportional to its radius cubed. If a sphere of diameter 1 cm has a mass of 4 grams, what diameter sphere has a mass of 108 grams?

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Question 667722: The weight of a sphere is proportional to its radius cubed. If a sphere of diameter 1 cm has a mass of 4 grams, what diameter sphere has a mass of 108 grams?
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
w+%28alpha%29+r%5E3
w=kr%5E3 where k is the constant of proportionality
mass 4 gm radius = 1/2cm
4=+k%2A%281%2F2%29%5E3
4=+k%2F8
k=32
mass = 108
k= 32
r=?
w=kr%5E3
108=32%2Ar%5E3
108%2F32+=r%5E3
27%2F8=r%5E3
take the cube root
3/2 = r
r= 1.5 cm
diameter is twice the radius.