The sun is shining and a spherical snowball of volume 210 ft3 is melting at a rate of 14 cubic feet per hour. As it melts, it remains spherical. At what rate is the radius changing after 3 hours?

Answer 1

Volume= 4/3 PI r^3

dV/dt=4PI r^2 dR/dt

you are given dV/dt as 14ft^2/hr

you are looking for dr/dt

so what is the radius at t=3?

210-14*3=4/3 PI r^3, solve for r.
put that r into the dV/dt equation, and solve for dR/dt

Answer 2

I followed these steps, but the answer is wrong. Is there a typo here?