Question

The ceiling of Katie’s living room is a square that is 15 ft long on each side. To decorate for a party, she plans to hang crepe paper around the perimeter of the ceiling and then from each corner to the opposite corner. Katie can buy rolls that each contain 20 ft of crepe paper. What is the minimum number of rolls she should buy? Show your work.

Answer 1

Answer: 6

Explanation:

The length of all sides of the square ceiling is 15 ft

Perimeter of the ceiling = 4 * length of each side = 15 * 4 = 60 ft

Distance from one corner to another corner i.e. BD and AC (in the figure below) forms the diagonals of the square ceiling

We know that,

Diagonal of a square = √(2) * a , where a is the length of the side of the square.

Therefore,

BD = AC = 15 √(2)

Thus,

Total crepe paper required = Perimeter of the ceiling + BD + AC = 60 + 15 √(2) + 12 √(2) = 102.43 ft

Crepe paper in each roll = 20 ft

Therefore,

Number of rolls required = 102.43 / 20 = 5.1215

Therefore, the minimum number of rolls she should buy is 6