The HR Department wants to know the appropriate sample size for its estimate of the mean number of absences in a quarter for all of the agency's employees. The mean number of absences is to be estimated within plus or minus 0.5 days of the population mean. The standard deviation is taken from the research shown in the following data. Use the 90 percent level of confidence.

Number of absences (in days) for a random sample of 11 employees
0	1	1	2	2	3	4	4	6	8	11

What is the appropriate sample size for this research?

n = ________