exhibit 9-4 a random sample of 16 students selected from the student body of a large university had an average age of 25 years. we want to determine if the average age of all the students at the university is significantly different from 24. assume the distribution of the population of ages is normal with a standard deviation of 2 years. the test statistic is . a. 1.645 b. 2.00 c. 1.96 d. .05