Target:pie charts and histograms.

Probabilities & Data Displays

Solve each proportion.

1.

2.

3. How many degrees are in a circle?

60

3

120

x

y

9

8

6

Pie Chart: A circle graph

that shows information as sectors of a circle.

Frequency: The # of times an item occurs.

Histogram: A bar graph that displays the frequency of

numerical data in equal-sized intervals.

Sally surveyed 20 students to find their favorite sport. 10 chose basketball, 3 chose baseball & 7 chose football. Draw a pie chart to display this data.

Write a proportion for basketball.

Solve. x = 180°

Write a proportion for baseball.

Solve. x = 54°

Football is the remaining sector.

360° – 180° – 54° = 126°

36020

10 x

36020

3 x

Example 1

Anthony interviewed classmates to determine their preference for sweets. He made the following pie chart. Find the probability someone will prefer chocolate.

Total number of students interviewed.

27 + 18 + 15 = 60

P(prefer chocolate) =

The probability someone will prefer chocolate is or 0.45 or 45%.

20

9

60

27

20

9

Example 2

a. Which interval in Erin’s histogram has the fewest number of students?

70-74. It only has 2 students.

b. Find P(student is in interval 62–66).

Students in interval: 5 Total students: 20

c. Use Erin’s information to predict the number of students in her school out of 860 students who are in the interval 62 – 66.

Proportion using the ratio from previous answer.

Use cross products to solve. 4x = 860 x = 215 About 215 students at Erin’s school are between 62 and 66 inches tall.

4

1

20

566)-62 intervalin isP(student

8604

1 x

Example 3

Exit next

Colin surveyed 10 students to find their favorite type of book.

3 chose sports books, 5 chose fiction, and 2 chose math.

Draw a pie chart to display this data.

Do you find it easier to make a pie chart or a histogram? Why? Do you find it easier to read a pie chart or a histogram? Why?

Probabilities and Data Displays

Lesson 15

Solve each proportion.

1.

2.

3. Bryce practiced shooting free throws. He made 12 of his 20 attempts. Tomorrow he is going to shoot 30 free throws. How many will he make?

60

3

120

x

y

9

8

6