How_To_Be_Good_At_Math

STATISTICS • LINE GRAPHS 289

Let’s see how tall Jacob was

aged 6. We find 6 on the

x axis and then go straight up.

This graph has kilometres

on the x axis and miles on

the y axis. The line lets us convert

from one unit to the other.

When we meet the green

line, we go straight across to

the y axis. This shows us that

Jacob was 110 cm tall at age 6.

To change 80 km into miles,

we go along the x axis until

we reach 80. Then we go up to

the line and across to the y axis,

where we read off 50 miles.

We can also work out Jacob’s

height at age 9^1 / 2. Going up

and across, the y axis tells us he

was probably 132 cm tall.

Go up from

x axis in a

straight line

Age 9^1 / 2

is midway

between

9 and 10

Read

off y

axis

To find the mile

equivalent, read up

to the line and along

Jacob grew 22 cm in

3 1 / 2 years

80 km is the same

as 50 miles

2

0

3

10

70

60

50

40

30

10

0

140

130

120

110

100

90

80

70

60

HEIGHT (cm)

AGE (years)

MILES

KILOMETRES

Jacob’s height

Conversion graphs Kilometres/miles conversion graph

A conversion graph uses a

straight line to show how two

units of measurement are related.

Reading line graphs

This graph tells us how Jacob grew

between the ages of 2 and 12. We

can see how tall he was at any

age by going up from the x axis to

the line, then across to the y axis.

We can also estimate his height

between yearly measurements.

4

20

5 6

30

7 8

40

9

50

10 11

60 70

12

80

150

160

170

90

288_289_Line_graphs.indd 289 29/02/2016 18:06