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A gallon of paint covers 20 ft2 of surface area. How many revolutions can an 8 in. wide paint roller with a diameter of 3 in. make before using up a 5-gal can of paint?

 May 1, 2020
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Mmmm....this is an interesting question  !!!!

 

Note that 20 ft^2  =  20 * 12^2  =  2880 in^2

 

So 5 gallons of paint must cover 5 * 2880  =  14400 in^2

 

Each revolution of the roller represents the lateral  surface area of a cylinder with a  radius of 1.5 in  and and a height of 8 in

 

So...the  surface area covered in one revolution  =  2pi * radius * height   =  2 pi (1.5) (8)  = 24 pi in^2

 

So.....the  number of approximate revolutions  is

 

Total area covered by 5 gallons of paint          14400

________________________________   = ________  ≈  191 revolutions

  Area covered by  one revolution                     24 pi 

 

 

cool cool cool

 May 1, 2020
edited by CPhill  May 1, 2020

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