SOLUTION: The cost of constructing a 5-foot by 7-foot deck is $192.50. If the cost varies jointly (section 9.5) as the length and width, then what does am 8-foot by 10-foot deck cost?

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Question 4444: The cost of constructing a 5-foot by 7-foot deck is $192.50. If the cost varies jointly (section 9.5) as the length and width, then what does am 8-foot by 10-foot deck cost?
Answer by rapaljer(4551) About Me  (Show Source):
You can put this solution on YOUR website!
Cost varies jointly as the length and width means that
C = kLW, where k is a constant.

Substitute all known values into the equation above and find k.
C = kLW
$192.50 = k(7)(5)
35k = 192.50

Divide both sides by 35:
k+=+192.50%2F35

Now, use this value of k in the original equation, and answer the question:
C = k*L*W
C=+%28192.50%2F35%29%2A+L+%2A+W
+C+=+%28192.50%2F35%29%2A10%2A8

Use a calculator??
C = $440

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