A researcher wants to know if using videos to illustrate concepts in class improves exam scores. He uses the videos before the first exam in his course and collects exam scores from the 62 students in...

A researcher wants to know if using videos to illustrate concepts in class improves exam scores. He uses the videos before the first exam in his course and collects exam scores from the 62 students in his class. On average, they score 78%, with a standard deviation of 5%. Use this description to answer the questions below.

a. What else does the researcher need to know in order to use a one-sample t test to test his hypothesis?

b. What is the null hypothesis for this study?

c. What tcrit should the researcher use in this study if his α = 0.05?