Question

chapter 1 activity painting a room
this exercise will review area formulas and basic operations. recall that the area of a rectangle is the product of the length and width of the rectangle. the perimeter of a rectangle is the sum of the lengths of the four sides of the rectangle.
the four walls of a classroom will be repainted.
the dimensions of the classroom are: height = 8 feet, length = 24 feet, width = 15 feet.

1. picture such a room; perhaps make a sketch of the walls and label the dimensions. then determine the area of each wall:

8·24 = 192 there are two walls with dimensions 8 feet and 24 feet
8·15 = 120 there are two walls with dimension 8 feet and 15 feet
now, one wall with the length of 24 feet does have a door which does not need to be painted. the door frame is 7 feet high and 3 feet wide. the wall opposite to the wall with the door has 4 windows, each measuring 4 feet by 2 feet.

1. when you remove the door and the windows, what is the surface area of the room that will be painted?

a gallon of primer will cover about 200 square feet.

1. how many gallons of primer should be purchased? it is unlikely you can buy part of a can, so keep this in mind when you answer this question.

Explanation:

Answer:

(1) Two walls have area 192 square - feet each, two walls have area 120 square - feet each.
(2) Total area of walls: \(2\times192 + 2\times120=384 + 240 = 624\) square feet. Area of door: \(7\times3 = 21\) square feet. Area of 4 windows: \(4\times(4\times2)=32\) square feet. Painted area: \(624-21 - 32=571\) square feet.
(3) \(571\div200 = 2.855\). Since we can't buy part of a can, 3 gallons of primer should be purchased.