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hi sasho i noticed that this question is on all the exams and im having a little trouble on it

number 4 on this exam:http://www.umanitoba.ca/student/exams/site/data/136151-041000-F-1903590565.pdf

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Start with S=4 Pi r^{2} and differentiate with respect to time. Get dS/dt=4 Pi 2r dr/dt; now substitute dS/dt and r at the given moment to compute dr/dt.

Then start with the volume formula V=(4/3)Pi r^{3} and again differentiate with respect to time; get dV/dt = (4/3)Pi 3r^{2} dr/dt; now substitute r at the moment (given) and dr/dt (found in the first part of the solution.)

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is the answer to the question 6 m^3/sec