Question

a drop of ink is placed in area at the rate of 1sq mm/sec. at what rate does the radius of the blot increase when its area is sq mm?

Answer 1

\[A=\pi r^{2}, dA/dt=2\pi r dr/dt\]
you have dA/dt and r so you can solve dr/dt

Answer 2

well i geuss you have A and can find r at least