Two samples are taken with the following sample means, sizes, and standard deviations x1x1 = 31 x2x2 = 38 n1n1 = 53 n2n2 = 50 s1s1 = 4 s2s2 = 2 We want to estimate the difference in population means using a 88% confidence level. What distribution does this require?

• z
• t, df = 77.44

What is ? What is the critical value for the confidence interval? Use Technology The 88% confidence interval is: 7.97<12<6.03-7.97<1-2<-6.03 Does this interval include 0? What does that decision mean?

• It excludes 0. The two population means are different.
• It does include 0. The two population means seem to be equal.