The Educational Testing Service (ETS) designs and administers the SAT exams. Recently the format of the exam changed and the claim has been made that the new exam can be completed in an average time of 120 minutes. A sample of 50 new exam times yielded an average time of 115 minutes. The standard deviation is assumed to be 2 minutes.
a) Set up the null and the alternative hypotheses to test whether average times to complete the exam has changed from 120 minutes.
b) Complete the remaining hypothesis testing steps using a=0.05.
c) Find the p value.
d) Based on the p value, what can you conclude about the average time to complete the new exam?