Refer to the alligator data in Table D.11 of the Data Bank. Using the data on testosterone x4 for male alligators, compare the means for the two lake regions.
(a) Should you pool the variances with these data?
(b) Find a 90% confidence interval for the difference of means between the two lakes. Use the approximate r procedure on page 413.
(c) Which population has the highest mean and how much higher is it?