Education: Tutoring In the article cited in Problem 17, the results of the following experiment were reported: Form 2 of the Gates-MacGintie Reading Test was administered to both an experimental group and a control group after 6 weeks of instruction during which the experimental group received peer tutoring and the control group did not. For the experimental group with n1 5 30 children, the mean score on the vocabulary portion of the test was x1 5 368.4 with sample standard deviation s1 5 39.5. The average score on the vocabulary portion of the test for the n2 5 30 subjects in the control group was x2 5 349.2, with sample standard deviation s2 5 56.6.

(a) Use a 1% level of signifi cance to test the claim that the experimental group performed better than the control group.

(b) Find a 98% confi dence interval for m1  m2. Explain the meaning of the con fi dence interval in the context of the problem.