A study was done on proctored and nonproctored tests. The results are shown in the table. Assume that the two samples are independent simple random samples selected from normally distributed populations, and do not assume that the population standard deviations are equal. Complete parts (a) and (b) below. Use a significance level 0.01 for both parts.

___________________________________________________________________

ProctoredNonproctored

12

n3432

x

x74.8683.25

s10.5118.27

_______________________________________________

a) Test the claim that students taking nonproctored tests get a higher mean score than those taking proctored tests.

b) Construct a confidence interval suitable for testing the claim that students taking nonproctored tests get a higher mean score than those taking proctored tests.