Relative Frequency Histogram

A relative frequency histogram uses the same information as a frequency histogram but compares each class interval to the total number of items. For example, the first interval ($1 to $5) contains 8 out of the total of 32 items, so the relative frequency of the first class interval is equation (see Table 1).

Table 1. Distribution of Items Sold at Garage Sale, Including Relative Frequencies

Class

Interval

Frequency

Relative Frequency

1

$1 to $5

8

0.25

2

$6 to $10

6

0.1875

3

$11 to $15

4

0.125

4

$16 to $20

2

0.0625

5

$21 to $25

4

0.125

6

$26 to $30

6

0.1875

7

$31 to $35

2

0.0625

The only difference between a frequency histogram and a relative frequency histogram is that the vertical axis uses relative or proportional frequency instead of simple frequency (see Figure 1).

Figure 1. Relative frequency histogram of items sold at a garage sale.

figure

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