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

27

27

18

18

x overbar

x

45.9

45.9

44.9

44.9

s

6.8

6.8

13.7

13.7

The confidence interval has a lower bound of

nothing

and an upper bound of

nothing

.

(Use ascending order. Round to two decimal places as needed.)