(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A spherical raindrops evaporates at a rate proportional to its surface area. If its radius is 3mm, and 1 hour later has been reduced to 2mm, find an expresssion for the raduis of the raindrops at anytime.

2. Relevant equations

[tex]Volume = \frac{4}{3}\pi R^3[/tex]

[tex]Area = 4\pi R^2[/tex]

3. The attempt at a solution

[tex]\frac{d}{dt}(\frac{4}{3}\pi R^3) = -k (4\pi R^2)[/tex]

[tex]4\pi R^3 \frac{d}{dt} = -k 4\pi R^2[/tex]

[tex]\frac{R dR}{dt} = -k[/tex]

then... how do I plug in 2 and 3 mm??

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# Homework Help: Integration Word Problem

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