A production manager wishes to determine if there is a difference in the number of production runs produced by the night shift and the day shift. A random sample of night and day shifts is selected, and the number of production units for each shift is recorded. The following are the results of the same:
σ n
Day Shift 27.4 6.4 60
Night Shift 18.3 5.9 60
a) Find a 90% confidence interval on the difference in the mean number of production units for the two shifts.
b) Calculate a 99% confidence interval for part a)
c) Compare the length of the intervals of the two confidence intervals obtained in a) and b).