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## Homework Statement

Leaking oil is forming a circular patch on the surface of the sea. The area of the patch is

increasing at a rate of 250 square metres per hour. Find the rate at which the radius of the patch

is increasing at the instant when the area of the patch is 1900 square metres. Give your answer

correct to 2 significant figures.

## Homework Equations

## The Attempt at a Solution

dA/dr = 2πr ... dA/dt = 250

therefore dr/dt = 250/2πr

I've tried 250/2πr = 1900 to find r but that doesn't seem to be correct :\

I'm not sure what I'm missing - please help, thanks