Assuming that both populations are normally distributed, construct a 90

90% confidence interval about mu 1 minus mu 2

12. (mu 1

1 represents the mean of the experimental group and mu 2

2 represents the mean of the control group.)

Experimental

Control

n

22

22

16

16

x overbar

x

45.7

45.7

43.9

43.9

s

6.3

6.3

9.3

9.3

The confidence interval has a lower bound of

nothing

and an upper bound of

nothing

.