Please help: Related rates

[dippind0ts]

the question ask for

Find the rate that the Earth's radius is increasing in mm/century from the accrual of meteoric and cometary dust, given that an estimated 20 million cubic-centimeters of dust is deposited on the earth every year, and the earth's radius is about 6.4 million meters. use formula for the volume of a sphere and the technique of related rates.

Im not exactly sure how to start or set this up. all i have so far is V= (4/3)pi*r^3

 

[stapel]

Find the rate that the Earth's radius is increasing in mm/century from the accrual of meteoric and cometary dust, given that an estimated 20 million cubic-centimeters of dust is deposited on the earth every year, and the earth's radius is about 6.4 million meters. use formula for the volume of a sphere and the technique of related rates.

Im not exactly sure how to start or set this up. all i have so far is V= (4/3)pi*r^3

Yes, you'll need the formula for the volume of a sphere.

You've been given the rate at which the volume is changing every year, in terms of cubic centimeters, so you have dV/dt. You are given the current radius value r, in meters. Convert one or the other unit, so you're working either in centimeters or meters, but not both.

If you differentiate the volume formula, what will result? What values can you plug in? With what will you be left? What can you solve for?