# A.1.12.3 Investigating Variability

Begin with the data: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 Clear the data from the spreadsheet again and use technology to find the mean, standard deviation, median, and interquartile range. Enter the values here:

How do the standard deviation and mean change when you **remove the greatest value** from the data set?

How do the standard deviation and mean change when you add a value to the original set that is **twice the greatest value**?

What do you predict will happen to the standard deviation and mean when you **remove the least value** from the original data set? Check to see if your prediction was correct.

What happens to the standard deviation and mean change when you add a value to the original set that is **equal to the mean**? Add a second value equal to the mean. What happens?

Add, change, or remove values from the original data set to answer the question: What appears to change more easily, the standard deviation or teh interquartiel range? Explain your reasoning.