The Back-To-Back Dotplot Shows the Number of Fatalities Per Year

question 67

Multiple Choice

The back-to-back dotplot shows the number of fatalities per year caused by tornadoes in a certain state for two periods: 1950-1974 and 1975-1999.Explain how you would summarize the centre and spread of each of the variables depicted in the dotplots.

• A)The distribution of the number of fatalities per year for the period 1950-1974 is unimodal and approximately symmetric.Therefore,we would be satisfied using the mean to summarize the centre and the standard deviation to summarize spread.For the period 1975-1999,the distribution of the number of fatalities per year is also unimodal,but skewed to the right.Therefore,we would prefer to use a median for centre and an IQR to summarize spread.
• B)The distribution of the number of fatalities per year for the period 1950-1974 is unimodal,but skewed to the right.Therefore,we would prefer to use a median for centre and an IQR to summarize spread.For the period 1975-1999,the distribution is also unimodal and approximately symmetric.Therefore,we would be satisfied using the mean to summarize the centre and the standard deviation to summarize spread.
• C)The distribution of the number of fatalities per year for the period 1950-1974 is bimodal.Therefore,we would prefer to use a median to summarize the centre and an IQR to summarize spread.For the period 1975-1999,the distribution of the number of fatalities per year is also bimodal,but skewed to the left.Therefore,we would prefer to use a mean for centre and a standard deviation to summarize spread.
• D)The distribution of the number of fatalities per year for the period 1950-1974 is unimodal and approximately symmetric.Therefore,we would prefer to use the median to summarize the centre and the standard deviation to summarize spread.For the period 1975-1999,the distribution of the number of fatalities per year is also unimodal,but skewed to the right.Therefore,we would prefer to use the mean for centre and an IQR to summarize spread.
• E)The distribution of the number of fatalities per year for the period 1950-1974 is unimodal but skewed to the right.Therefore,we would prefer to use a median to summarize the centre and IQR to summarize spread.For the period 1975-1999,the distribution of the number of fatalities per year is also unimodal and skewed to the right.Therefore,we would prefer to use a median for centre and an IQR to summarize spread.

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