Question

Constructing Frequency Distributions. In Exercises 11–18, use the indicated data to construct the frequency distribution. (The data for Exercises 13–16 can be downloaded at TriolaStats.com.)

Tornadoes Listed below are the F-scale intensities of recent tornadoes in the United States. Construct a frequency distribution. Do the intensities appear to have a normal distribution?

040011100012011010111100100100111300020300000

Short answer

The following frequency distribution is constructed for the F-scale intensities of tornadoes:

F-scale intensity	Frequency
0	24
1	16
2	2
3	2
4	1

The intensities of the tornadoes do not appear to follow a normal distribution.

Step-by-step solution

Given information

Data are given on the F-scale intensities of some recent tornadoes.

Frequency distribution

A frequency distribution is a tabulated representation of the number of values that fall in each interval. It is used to depict the numerical data.

If the frequencies gradually rise from a low value, reach a maximum value, and then eventually fall, the frequency distribution is said to follow the normal distribution.

In addition, the frequencies on both sides of the peak value should appear symmetric.

Construction

Here, as the data contains only a few discrete values (0, 1, 2, 3, and 4), there is no need to compute the closed class intervals.

The discrete numerals are utilized to complete the frequency distribution by counting the number of times each discrete value appears in the data.

Here, 0 appears 24 times, 1 appears 16 times, 2 appears 2 times, 3 appears 2 times, and 4 appears 1 time.

Thus, the following frequency distribution is constructed:

F-scale intensity	Frequency
0	24
1	16
2	2
3	2
4	1

It can be observed that the frequencies start from a high value and then continue to decline until the last class interval. They do not seem to follow the pattern required for the distribution to be normal.

Thus, the given frequency distribution does not appear to follow a normal distribution.