The personnel director of a large corporation wished to study absenteeism among clerical workers at the corporation's central office during the year. A random sample of 25 clerical workers reveals the following:
Absenteeism: X= 9.7 days, S = 4.0 days
12 clerical workers were absent more than 10 days
A. Construct a 95% confidence interval estimate of the mean number of absences for clerical workers during the year.
B. Construct a 95% confidence interval estimate of the population proportion of clerical workers absent more than 10 days during the year.
C. What sample size is needed to have 95% confidence in estimating the population mean to within +- 1.5 days if the population standard deviation is 4.5 days?
D. What sample size is needed to have 90% confidence in estimating the population proportion to within +- 75 if not previous estimate is available?
The solution provides step by step method for the calculation of confidence interval for mean and proportion and sample size. Formula for the calculation and Interpretations of the results are also included. Interactive excel sheet is included. The user can edit the inputs and obtain the complete results for a new set of data.