Menstrual cycle length. Exercise 11.11 calculated the mean length of menstrual cycles in an SRS of n=9 women. The data revealed xbar=27.78 days with standard deviation s=2.906 days.

1. Calculate a 95% confidence interval for the mean menstrual cycle length.

Assumptions have already been checked above...

1. Based on the confidence interval you just constructed, is the mean menstrual cycle length significantly different from 28.5 days at alpha=0.05 (two-sided)? Is it significantly different from mu=30 days at the same alpha-level? Explain.