Shoe size data, collected at the beginning of the semester, can be separated according to gender. Let the WCU female population be represented by mu subscript F, and the WCU male population be represented by mu subscript M. The mean, standard deviation and sample size for both male and female shoe size date is shown in the table below:

X S n Female UF 18.4 1.29 |17 Male UM 11.3 1.81 16 What is the upper boundary of a 90% confidence interval for the difference of population means IF - HM