A personnel manager at a large firm needs to estimate the mean length of stay,μ of its employees. She takes a random sample of employees and finds the sample mean () to be 25 years.

a) Use the above data, = 25, to find a 90% confidence interval for μ if the employee sample size is 64, and σ = 16.
b) What is the appropriate distribution (z or t)?
c) What is the numerical value of (z or t)?
d)What is the Confidence Interval? (Show equation with filled in numerical values. Calculate answer.)
e) Interpret the meaning of the Confidence Interval for the mean length of stay, m of the employees in the large firm? (Concise answer.)