1. In a study considering any differences in weight loss among rats (two groups:stressed vs. unstressed), the table below lists the 2 groups, the number in each, themean amount of weight lost (in grams) and the standard deviation of each group.The question is to find the 90% confidence interval:

Group A Stressed: n=29 x-bar=2.7 s=0.22

Group B Unstressed: n=21 x-bar=2.5 s=0.21

Which formula will you use: ____________________

Worked out answer: