Homework 3 - Descriptive Statistics and Boxplots

Which of the following summary measures cannot be directly calculated from a boxplot?

Sample size

Which is more affected by skewness, the IQR or standard deviation?

Standard Deviation

If you add the same positive number to every value of a data set what happens to the standard deviation?

does not change

If a data set is skewed to the left, how will the mean and median compare?

the mean will be less than the median

An outlier in a data set can significantly affect the value of the mean but not the median.

true

Suppose your data represent revenues from a group of 20 stores in a retail chain across the country, and revenue is measured in millions of dollars. The standard deviation of this data set would also be measured in millions of dollars.

true

standard deviation can never be negative

true

The government is interested in cars using less fuel, so they decide to provide a 'gas guzzler tax' for those who own vehicles that get bad gas mileage (low numbers for mpg). What is cutoff for MPG if you want only 25% of the cars to receive this tax?

33.750 mpg