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45 votes
The paint cost 17.98 per gallon and the primer cost 21.98 per gallon use the room dimensions to figure out how many cans of primer you’ll need and how many cans of paint you will need to do 2 coats of each. (1 gallon covers 400 sq. Ft.

The paint cost 17.98 per gallon and the primer cost 21.98 per gallon use the room-example-1
User Vhristoskov
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2.8k points

1 Answer

24 votes
24 votes

Since we are painting the room,but not the door and the window, we need to find the area of the room we're painting.

The area of walls is:


4(18(15))=1080ft^2

Why? because you have 4 walls (2 of them are the length times the height)

We have to find out the area of the door and the window to subtract it from the total area of the room. So:

First of all we need to convert inch to feet, therefore:


\begin{gathered} 1\text{ inch - 0.0833 feet} \\ 120\text{ inch - x} \\ x=\text{ }\frac{\lparen120in\rparen\lparen0.0833feet\rparen}{1\text{ inch}} \\ x=\text{ 9.996 feet} \\ \\ x=\text{ }(\lparen80in\rparen\lparen0.0833feet\rparen)/(1in) \\ x=\text{ 6.664 feet} \\ \\ x=\frac{\lparen90in\rparen\lparen0.0833feet\rparen}{1\text{ in}} \\ x=\text{ 7.497 feet} \\ \\ x=\frac{\lparen40in\rparen\lparen0.0833feet\rparen}{1\text{ in}} \\ x=\text{ 3.332 feet} \end{gathered}


\begin{gathered} Area\text{ door= l x w} \\ Adoor=\text{ 7.497 ft x 3.332 ft} \\ Adoor=\text{ 24.98 ft}^2 \\ \\ Awindow=\text{ 9.996 ft x 6.664 ft} \\ Awindow=\text{ 66.6133 ft}^2 \\ \end{gathered}

Now, the total area we need to paint will be:


\begin{gathered} Area\text{ paint= Totalarea - Awindow -Adoor} \\ Area\text{ paint= 1080 ft}^2\text{ -66.6133 ft}^2\text{ -24.95 ft}^2 \\ Area\text{ paint= 988.44 ft}^2 \end{gathered}

If 1 gallon covers 400 sq. feet, then we need to do the divide the area we need to paint by the amount of square feet one gallon covers:


\frac{988.44\text{ ft}^2}{400\text{ ft}^2}=\text{ 2.472 gallons }

If she need to do 2 coats of each, then we have to multiply the gallons by 2:


2.472\text{ gallons x 2= 4.942 gallons = 5 gallons approximately of paint. }

Then, to paint the room with 2 coats each, they will need 5 cans of paint and 5 cans of primer.

User Adrian Toman
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