posted by Michael .
According to a study by the Centers for Disease Control, the national mean hospital stay after childbirth is 2.1 days. Reviewing records at her own hospital, a hospital administrator calculates that the mean hospital stay for a random sample of 81 women after childbirth is 2.3 days with a standard deviation of 1.2 days.
The 95% confidence interval is ( days, days) Show two decimal places in your responses.
How do I do this?
95% = mean ± 1.96 SEm
SEm = SD/√n