1.6 Tables and Graphs

GOAL 1 Use tables to organize data.

GOAL 2Use graphs to organize real-life data, such as the amounts of various foods consumed (Example 2).

What you should learn

To help you see relationships among real-life data, such as the average cost of making a movie.

Why you should learn it

GOAL 1 USING TABLES TO ORGANIZE DATA

Remember: A table is just one way to organize data. We need to organize it to make it easier to understand.

EXAMPLE 1

1.6 Tables and Graphs

Extra Example 1

The data in the table represents the number of worldwide shipments of personal computers, in millions. During which 2-year period did the number of shipments increase the most?

Solution:

PC Shipments (millions)

Year ’90 ’92 ’94 ’96 ’98

PCs 23.7 32.4 47.9 70.8 98.4

Find the difference in each 2-year period.

The greatest increase in shipments occurred from 1996-1998.

Change ---- 8.7 15.5 22.9 27.6

GOAL 2 USING GRAPHS TO ORGANIZE DATA

BAR GRAPHS—The bars may be either vertical or horizontal.

1.6 Tables and Graphs

EXAMPLE 2

LINE GRAPHS—Connect the data points with straight lines; do not draw curves.

A graph for the data in Extra Example 1 is shown. Is the graph misleading? Explain.

PC Shipments (millions)

Year ’90 ’92 ’94 ’96 ’98

PCs 23.7 32.4 47.9 70.8 98.4

Extra Example 2

PC Shipments

1990 1992 1994 1996 19980

25

50

75

100

Year

mil

liio

ns

The bar graph is not misleading since the vertical scale is consistent.

Drawing GraphsAll graphs need:

1. Title

2. Axis labels

3. Appropriate scaleDoes it go beyond the largest number?Does it show the differences in data?

4. Consistent scale

5. Neatness

The data in the table represents the number of households in the U.S. in millions.

Checkpoint

Year ’60 ’70 ’80 ’90 ’00

No. 52.8 63.4 80.8 93.3 103.2

a. During which 10-year period did the number of households increase the most?

1970 to 1980

b. Draw a bar graph to represent the data.

Checkpoint (cont.)Year ’60 ’70 ’80 ’90 ’00

No. 52.8 63.4 80.8 93.3 103.2

U.S. Households

1960 1970 1980 1990 20000

20

40

60

80

100

120

Year

Nu

mb

er

(mill

ion

s)

EXAMPLE 3

TITLE

LABELS

SCALE

SCALE

Extra Example 3

Year ’60 ’70 ’80 ’90 ’00

No. 17.4 21.4 27.8 34.3 39.0

The data in the table represents the number of people over age 65 in the U.S. in millions.

a. Draw a line graph.U.S. Population Over Age 65

0

10

20

30

40

50

’60 ’70 ’80 ’90 ’00

Year

Num

ber (

mill

ions

)

Extra Example 3 (cont.)

U.S. Population Over Age 65

0

10

20

30

40

50

’60 ’70 ’80 ’90 ’00

Year

Num

ber (

mill

ions

)

Year ’60 ’70 ’80 ’90 ’00

No. 17.4 21.4 27.8 34.3 39.0

b. During which 10-yr period was there the least increase?

Answer: from 1960 – 1970.

Think: How does the bar graph show the answer to this question?

The steeper the line, the greater the difference between the points.

Checkpoint

a. Draw a line graph for the data in Extra Example 1.

PC Shipments (millions)

Year ’90 ’92 ’94 ’96 ’98

PCs 23.7 32.4 47.9 70.8 98.4

PC Shipments

020

4060

80100

120

1990 1992 1994 1996 1998

Year

Nu

mb

er (

mil

lio

ns)

b. During which two-year period did the number of shipments increase the least? 1990-1992

QUESTIONS?