Introduction to Related Rates Practice Test

A circle’s radius $r(t)$ changes and its area is $A=\pi r^2$; which setup finds $\dfrac{dr}{dt}$ from $\dfrac{dA}{dt}$?

An expanding cube has volume $V(t)=s(t)^3$; which equation correctly relates $\dfrac{dV}{dt}$ and $\dfrac{ds}{dt}$?