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A propane storage tank for a home is shaped like a cylinder with hemispherical ends, and a cylindrical portion length that is 4 times the radius.

The formula S=12pi(3V/16pi)^(2/3) expresses the surface area of a tank with this shape in terms of its volume.

 

A. Use the properties of rational exponents to rewrite the expression for the surface area so that the variable V is isolated. Then write the approximate model with the coefficient rounded to the nearest hundredth.

 

B. What is the surface area in square feet for a tank with a volume of 150 ft^2?

 Nov 12, 2015
 #1
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I'm assuming this is supposed to be :

 

S=12pi(3V/[16pi])^(2/3)

 

(A)  exponentiate both sides to the 3/2 power

 

S^(3/2)  = 12pi ( 3V/[ 16 pi])

 

S^(3/2)  = (36/16) V

 

S^(3/2)  = ( 9/4)V

 

S^(3/2)  = 2.25V

 

[ S^(3/2)] / 2.25   = V

 

(1 / 2.25)S^(3/2)   = V

 

[0.44]S^(3/2)  = V       [the 0.44 is the "rounded" coefficient]

 

 

(B)  12pi(3[150]/[16pi])^(2/3)  = about 162.54  sq ft

 

BTW - this is correct based on my interpretation of the formula......if the "pi"  in the parentheses in the formula was not supposed to be in the denominator, a clearer  form would have been  :

 

S = S=12pi[ (3/16)Vpi ] ^(2/3).........I did not interpret it in that way.......I interpreted "16 pi" as the  whole denominator

 

 

 

cool cool cool

 Nov 13, 2015

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