Frequency Distributions Tables (continued)

Example 2:

In a second test, the same psychologist wonders how long it takes 20 children to color a set of drawings. She now records the following scores in minutes:

31, 43, 36, 29, 41, 40, 33, 37, 28, 39, 30, 44, 35, 28, 40, 39, 32, 36, 27, 38

The following grouped frequency distribution table displays these scores.

Grouped Frequency Distribution

$${\rm X}$$	f	$$\text{p = f/N}$$	$$\text{percentage = p}\times \text{100}$$
25-29	4	0.2	20%
30-34	4	0.2	20%
35-39	7	0.35	35%
40-44	5	0.25	25%

N = 20, the sum of p is 1.0, and the sum of the percentages is 100% in this example.

For these same data, the following grouped frequency table with smaller intervals would also be acceptable:

Grouped Frequency Distribution with Smaller Intervals

$${\rm X}$$	f	$$\text{p = f/N}$$	$$\text{percentage = p}\times \text{100}$$
26-27	1	0.05	5%
28-29	3	0.15	15%
30-31	2	0.1	10%
32-33	2	0.1	10%
34-35	1	0.05	5%
36-37	3	0.15	15%
38-39	3	0.15	15%
40-41	3	0.15	15%
42-43	1	0.05	5%
44-45	1	0.05	5%