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January 30, 2015

January 30, 2015

Posted by **jonh** on Sunday, March 10, 2013 at 4:54pm.

- Math -
**Reiny**, Sunday, March 10, 2013 at 5:25pmlet the radius be r

let the height be h

Volume = πr^2h

πr^2h = 400

h = 400/(πr^2)

cost = different prices x surface areas

= .03(2πrh) + 2(.06) πr^2

= .03[2πr(400/πr^2) + 4πr^2]

= .03[ 800/r + 4πr^2]

d(cost)/dr = .03[ -800/r^2 + 8πr] = 0 for a min of cost

800/r^2 = 8πr

100/π = r^3

r = 3.169

h = 400/(π(3.169)^2) = 12.679

check my arithmetic

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