Consider the following data drawn independently from normally distributed populations:
x1 = -10.5
x2 = -16.8
s12 = 7.9
s22 = 9.3
n1 = 15
n2 = 20
a. Construct the 95% confidence interval for the difference between the population means. Assume the population variances are unknown but equal.
b. Specify the competing hypotheses in order to determine whether or not the population means differ.
c. Using the confidence interval from part a, can you reject the null hypothesis? Explain.