Construct and Interpret Confidence Intervals About the Population Mean Difference $90 \%$

Construct and Interpret Confidence Intervals about the Population Mean Difference of Matched -Pairs Data
-Seven randomly selected plants that bottle the same beverage implemented a time management program in hopes of improving productivity. The average time, in minutes, that it took the companies to produce the same quantity of bottles before and after the program are listed below. Assume the two population distributions are normal. Construct a $90 \%$ confidence interval for $\mu _ { d }$ . Assume that the paired data came from a population that is normally distributed.

A) $( 0.21,10.93 )$
B) $( 1.60,9.54 )$
C) $( - 0.22,11.36 )$
D) $( - 22,33.3 )$