A spherical snowball, related rates

Question

A spherical snowball is melting. Its radius is decreasing at 0.8 cm per hour when the radius is 20 cm. How fast is its volume decreasing at that time?

NOTE: Enter the exact value or round to three decimal places.

The volume is decreasing by _____ cm^3 per hour.

I have been trying this for a while, I have tried the answers -1280π and -4021.239, however, both of these answers are incorrect. Could anyone please solve this step by step and explain. I am on my final attempt, please help.

Answer 1

v = 4πr³/3

Therefore by the Chain Rule,

dv/dt = 4πr²dr/dt.