Home > CC1 > Chapter 4 > Lesson 4.2.3 > Problem4-74

4-74.

Cecelia wants to measure the area of her bedroom floor. Should she use square inches or square feet? Complete parts (a) through (c) below as you explore this question.

1. Write a sentence to explain which units you think Cecelia should use.

Square inches are good for measuring the area of things such as your desk or a piece of paper.
Do you think they would also be good for measuring the area of your room? Make sure to explain
your reasoning.

2. If Cecelia’s bedroom is $12$ feet by $15.5$ feet, what is the area of the bedroom floor? Show how you got your answer.

To get you started, here is a generic rectangle representing the area of Cecelia's room.

 Generic rectangle top edge left$15\ \text{feet}$ top edge right$0.5 \text{ feet}$ left edge top$10 \text{ feet}$ interior top left blank interior top right blank left edge bottom$2 \text{ feet}$ interior bottom left blank interior bottom right blank
3. Find the perimeter of Cecelia’s bedroom floor. Show how you got your answer.

• The perimeter is the distance you would travel if you walked the length of each wall in Cecelia's room.
Thus, the following expression represents the perimeter of the room: $12 + 15.5 + 12 + 15.5$.

$55$ feet