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April 1, 2015

April 1, 2015

Posted by **ankur** on Thursday, June 6, 2013 at 3:20am.

(a)3.33 in2/sec

(b)3.67 in2/sec

(c)3.11 in2/sec

(d)none of these

- maths -
**Reiny**, Thursday, June 6, 2013 at 8:12amV = (4/3)πr^3

dV/dt = 4πr^2 dr/dt

when r = 6 , and dV/dt = 10

10 = 4π(36) dr/dt

dr/dt = 10/(144π) = 5/(72π)

A = 4πr^2

dA/dt = 8πr dr/dt

when r = 6

dA/dt = 8π(6)(5/(72π) )

= 30/9 = 10/3

= appr 3.33 -------> looks like a)

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