A health educator wants to evaluate the effect of a dental film on the frequency with which children brush their teeth. A random selection of 8 children are used for the experiment. First, a baseline of the number of times the children brush their teeth over a month's period is established. Next, the children are shown the dental film and again the number of teeth brushings are recorded for a month. The following data are recorded:

Subject 1 2 3 4 5 6 7 8

After Film 28 29 25 30 25 27 28 24

Baseline 25 28 22 30 26 24 25 22

Difference 3 1 3 0 -1 3 3 2

Using alpha 0.05_{2-tail ,} calculate a 95% confidence interval for the data.