The personnel director of the large corporation desires to study absenteeism among clerical workers at corporation's central office during the year. A random sample of 25 clerical workers reveals the following:
- Absenteeism: X (with line over top) = 9.7, S = 4.0 days.
- 12 clerical workers were absent more than 10 days.
a. Construct a 95% confidence interval estimate for the mean number of absences for clerical workers during the year.
b. Construct a 95% confidence interval estimate for the population proportion of clerical workers absent more than 10 days during the year.
Suppose that the personnel directior also wishes to take a surver in a branch office. Answer these questions.
c. What sample size is needed to have 95% confidence in estimating the popularion mean absenteeism to within + - 1.5 days if the population standard is estimated to be 4.5 days?
d. How many clerical workers need to be selected to have 90% confidence in estimating the population proportion to within + - 0.075 if no prevois estimate is available?
e. Based on c and d, what sample size is needed if a single survey is being conducted?