### Home > MC2 > Chapter 2 > Lesson 2.2.3 > Problem2-71

2-71.

Erica is making a quilt like the one shown at right. She is going to give each square to a different person to decorate before she sews them together.

1. If she gives people squares at random, what is the probability that she will give her mother a gray square?

You can write probability using a fraction:
$\frac{\# \text{ of squares we're looking for}}{\# \text{ of total squares}}$

Now count the number of gray squares, then the number of total squares to get the probability.

2. What is the probability that she will give her brother a gray or a black square to decorate?

Refer to part (a) for help.

3. What is the area of the white region? What is the perimeter of the white region?

To find the area, count the number of squares since each is one square unit. To find the perimeter, use the toothpick method you learned in chapter one.

Area $= 10$ square units
Perimeter $= 18$ units