understanding Standard Deviation. The following four sets of 7 numbers all have a mean of 9.

{9, 9, 9, 9, 9, 9, 9,} {8, 8, 9, 9, 9, 10, 10}

{8, 8, 8, 9, 10, 10, 10} {6, 6, 6, 9, 12, 12, 12}

a. Make a histogram for each set.

b. Give the five-number summary and draw a boxplot for each set.

c. Compute the standard deviation for each set.

d. Based on your results, briefly explain how the standard deviation provides a useful single-number summary of the variation in these data sets.