6th Grade Math Textbook, Fundamentals

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9-13

Draw your circle graph.

Use a compass to draw a circle.

Make a radius using a straightedge.

Element Percent (%)

Oxygen 65

Carbon 18

Hydrogen 10

Nitrogen 3

All others 4

Remember:To find a percentage of a

number, multiply the number by the decimal

or fraction equivalent to the percent.

Element Percent (%) Multiply in sectorDegrees

Oxygen 65 0.65• 360 234

Carbon 18 0.18• 360 64.8

Hydrogen 10 0.10• 360 36

Nitrogen 3 0.03• 360 10.8

All others 4 0.04• 360 14.4

Totals: 100% 360

Update your skills. See pages 412 XIII, 414 XVII.

Make a Circle Graph

Objective To make a circle graph to display a set of data

The table shows the major elements that make up a typical
adult’s body. Why is a circle graph a good way to display this
data? How can you make a circle graph to display this data?

A is used to show parts of a whole.

You can make a circle graph by constructing sectors

of the circle in sizes that match the given data.

• Each labeled section of the circle will represent
  one of the elements in the table, and each section
  will be formed by a central angle.


• Use the data in the Percent column of the table to
  find the measure of each central angle.


• Use a decimal or fraction equivalent of each
  percent to find that percentage of 360.

circle graph

Start by creating the section for oxygen. Since

360 

 234 

 126

 , use a protractor to draw a

126

 central angle. The rest of the circle will be

the section representing oxygen.

Oxygen

234

65%

126

• There are 360 in a circle.


• To find the size of a sector, determine
  the measure of its central angle. You
  can do this by finding the percent of
  the circle that the sector represents.

Key Concept

• To find the size of the central angle of a sector
  when you know what percent of the circle
  the sector represents, multiply 360 by the decimal
  or fractional equivalent of the percent.
  The result is the percentage of 360 that is
  the measure of the central angle of the sector.


• To find the size of the central angle of a sector
  given data only, first calculate the percent for
  each piece of data. Then multiply 360 by the
  decimal or fraction equivalent to that percent.