The length, width and height of the wall of room is 12.0 ft, 15.0 ft and 9 ft respectively. To calculate the gallons of paint to paint the room with two coats, first calculate the surface area of room that needs to be coated.
The total surface are of room without ceiling will be:
[tex]A=2(l\times h)+2(w\times h)[/tex]
Here, l is length, h is height and w is width of the room.
Putting the values,
[tex]A=2(12.0 ft\times 9 ft)+2(15.0 ft\times 9 ft)=486 ft^{2}[/tex]
Since, 1 gallon of paint is used for area [tex]374 ft^{2}[/tex], for [tex]1 ft^{2}[/tex] of area, volume of paint used will be 0.00267 gallon.
Thus, volume of paint used for area [tex]486 ft^{2}[/tex] will be:
[tex]V=486 ft^{2}\times 0.00267gallon/ft^{2}\approx 1.3 gallon[/tex]
The above volume is for 1 coat of paint, for 2 coats volume will be:
[tex]V=2\times 1.3=2.6 gallon[/tex]
Therefore, paint required to paint room with two coats is 2.6 gallon.
