SOLUTION: how many cans of paint are needed to paint both the interior and exterior of an open conical shaped tank that has an 8 ft base radius and is 15 ft tall? one can covers 200 square f

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Question 465383: how many cans of paint are needed to paint both the interior and exterior of an open conical shaped tank that has an 8 ft base radius and is 15 ft tall? one can covers 200 square feet.
a. 3
b. 4
c 5

Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!
c. 5 cans of paint.
S+=+pi%2Ar%2Asqrt%28r%5E2+%2B+h%5E2%29 gives the lateral surface area of the cone.
r = 8, h = 15 ==> S+=+136pi square ft, the lateral surface area.
Since both inside and outside are to be painted, we need paint that will cover an area of 272pi sq.ft. Dividing this by 200, we get 4.272 approximately.
Hence 5 cans of paint are needed.