Chapter 11.10, Problem 29PPSE

Solution

a)

To plot: The histogram of the data of the number of tornadoes recorded in the U.S. in 2008 monthly.

The histogram of the given data is shown below

  

Given:The given data of the number of tornadoes recorded in each month in the U.S. in year 2008.

Month	No. of tornadoes
1	84
2	147
3	129
4	189
5	461
6	294
7	93
8	101
9	111
10	21
11	20
12	40

Plot:

The data is entered in excel in two columns. Select the data and insert a column chart and get a graph. Now right-click on the graph and click on format data series and change the gap width accordingly and also name the labels to get the following graph.

  

b)

To explain: The histogram for the data of the number of tornadoes recorded monthly is distributed normally or not.

The data of the number of tornadoes recorded monthly in the U.S. in 2008 cannot be approximated as a normal curve.

Plot:Drawing a normal sketch over the histogram looks like this as shown below

  

Interpretation:

The data has a tail to its right side and is skewed to the right slightly. Thus the data of the number of tornadoes cannot be approximated as a normal curve.

c)

To explain: Whether it is appropriate to use a normal curve to estimate the percentages of tornadoes during specific months of the year.

It is not appropriate to use a normal curve to estimate the percentages of tornadoes that occurred during a month.

Given:

The histogram of the data of the number of tornadoes that occurred during each month of the year is skewed to the right.

Interpretation:

The histogram of the data of the number of tornadoes that occurred during each month of the year is skewed to the right. Thus a normal curve cannot be used to estimate the percentages of tornadoes that occurred in specific months of the year.