Algebra 1 Common Core Student Edition, Grade 8-9

skills

Handb

Ci r cl e Gr a p h s

A circle graph is an efficient way to p re sen t certain types of data. The entire

circle represents all of th e data. Each section of th e circle represents a p a rt of the

whole an d can be labeled w ith th e actual d ata or th e d ata expressed as a fraction,

decim al, or percent. The angles at th e center are central angles, an d each angle is

p roportional to th e p ercen t or fraction of the total.

Ex a m p l e

Students at a high school were asked to pick their favorite instrument.

The table at the right shows the num ber of students w ho ch ose each

instrument. Draw a circle graph for the data.

St e p 1 Add to find th e total num ber.

35 + 103 + 150 + 182 = 470

St e p 2 For each central angle, set up a pro p o rtio n to find th e m easure.

Use a calculator to solve each proportion.

35

470

a

360°

; 2 7 °

103

470

. b
360°

150

470

b « 79°

c

360°

■ 1 1 5 °

182

470

d

360°

= 1 3 9 °

Favorite Musical Instruments

1

Number of Students

Bass^35

Drum s 103

Piano 150

G u ita r 182

St e p 3 Use a com pass to draw a circle.

Draw th e approxim ate central

angles using a protractor.

St e p 4 Label each sector.

r

139° ^

1 115° 27°]

L w

Favorite Musical Instruments

a. Use the data in th e table to draw a circle graph.

b. Approximately what percent of students

ride th e bus?

c. Approximately how m an y tim es m ore students

walk th a n ride in a car?

2. Data Collection Survey your class to find out how they get to school. Use th e
   data to draw a circle graph.

Methods of Transportation

Transportation Method W alk Bicycle Bus Car

Number of Students^252135 43281