Lucy decides to paint only the walls of 3 bedrooms in her house. Each room has a door, a closet door, and a window. She is only applying 1 coat of paint to the walls. Each room is 14 feet by 12 feet with 8-foot ceilings. Each door has dimensions 6.5 feet by 2.5 feet. Each window has dimensions 4.5 feet by 3 feet. 1 gallon of paint with cover 350 square feet. Paint is sold in 1-gallon containers. Enter the minimum number of 1-gallon cans of paint she need.
The surface area of the walls of the rooms is 14 feet * 8 feet * 2 + 12 feet * 8 feet *2= 416 feet^2. Since you dont paint doors and windows, you subtract the surface area of them. The doors have a surface area of 16.25 feet^2. The window has a surface area of 13.5 feet^2. From this, you find that you paint 416 feet -(16.25 feet * 2 + 13.5 feet)= 370 feet^2. Since there are 3 rooms you multiply this by 3 to get 1110 feet^2. Since each galloon covers 350 feet^2, then you need 1110/350= 3.171428571 gallons. But since you cannot get part of a gallon you need 4 gallons.
Hope it helps!