Dr. Whoosit is conducting an experiment to test whether eating chocolate has an effect on memory. 100 students are randomly selected for the experiment. Each student is given a standard-sized Hershey bar which they eat. 30 minutes later, Dr. Whoosit presents each student with a list of 30 words and asks them to memorize them. After 10 minutes, Dr. Whoosit takes the list and asks each student to write down as many words as they can recall. The population average on this kind of test is µ = 18 and the standard deviation is ? = 5. Using ? < .05, the critical values of z for this experiment are ±1.96.

a. What is the expected value of M for the sampling distribution?

b. What is the standard error for the sampling distribution?

c. Is this a one- or a two-tailed test?

d. The 100 students had an average number of words recalled of M = 20. What is the z-score for this sample mean?

e. Comparing the test statistic calculated in (d) with the critical values of z for this experiment, does the sample fall in the critical region of the sampling distribution [yes/no]?

f. What is your decision regarding the null hypothesis[accept/reject]?