Archeologists have studied sizes of Egyptian skulls in an attempt to determine whether breeding occurred between different cultures. Listed below are the widths (mm) of skulls from 150 A.D. Construct a 90% confidence interval estimate of the mean skull width.
128.3 138.1 125.6 132.2 143.1 134.9 138.9 128.9
____ mm < u < ____ mm ( round to 2 decimal places)