SOLUTION: The cost of a pizza varies directly with the square of its radius. If the cost of the pizza is $8.00 when the radius is 8 inches, find the cost when the radius increases to 10 inch

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Question 385272: The cost of a pizza varies directly with the square of its radius. If the cost of the pizza is $8.00 when the radius is 8 inches, find the cost when the radius increases to 10 inches.
Answer by mananth(16946) About Me  (Show Source):
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The cost of a pizza varies directly with the square of its radius. If the cost of the pizza is $8.00 when the radius is 8 inches, find the cost when the radius increases to 10 inches.
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Cost c proportional to r^2
c%28alpha%29r%5E2
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c=kr%5E2 where k is the constant of proportionality
r=8 c =8
plug these values
8=k%2A8%5E2
divide both sides by 8^2
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k=8/8^2
k=1/8
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k=1/8 r=10
c=kr^2
c=1/8*10^2
c=100/8
c=$ 12.50
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m.ananth@hotmail.ca