9514 1404 393
Answer:
r = 2
Step-by-step explanation:
"A varies inversely with r cubed" means the relation is of the form ...
A = k/r³
We can find the value of k as ...
k = Ar³ = 72·5³ = 9000 . . . . . . . multiply the above relation by r³
And we can solve this for r to get ...
r³ = 9000/A . . . . . . divide by A
r = ∛(9000/A) . . . . . take the cube root
So, for A = 1125, we have ...
r = ∛(9000/1125) = ∛8
r = 2
