x1 = 20, s1 = 6, n1 = 20, . x2 = 24, s2 = 2, n2 = 15
a. Left-tailed test, α = 0.05
b. 90% confidence interval
We have provided summary statistics for independent simple random samples from two populations. In each case, use the nonpooled t-test and the nonpooled t-interval procedure to conduct the required hypothesis test and obtain the specified confidence interval.