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Suppose you are an elementary school teacher. You want to order a rectangular bulletin board to mount on a classroom wall that has an area of 250 square feet. Suppose fire code requirements allow for no more than 30% of a classroom wall to be covered by a bulletin board. If the length of the board is three times as long as the width, what are the dimensions of the largest bulletin board that meets fire code?

 Jan 16, 2020
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Max  area of   bulletin board =  .30 *  250  =   75 sq ft

 

And we know that    L  =  3W

 

So  we have that

 

W L  =  75

 

W (3W) = 75

 

3W^2 = 75        divide both sides by  3

 

W^2  = 25       take the positive root

 

W  =  5

 

So  L  =3(5)  = 15

 

So....the dimensions  are     5 x 15

 

 

cool cool cool

 Jan 16, 2020

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