Each student in a class of 30 was assigned one random line of a random number table. Each student then counted the even-numbered digits in a 30-digit line.
a. On average, in the list of 30 digits, how many even-numbered digits would each student find?
b. If each student found an 80% confidence interval for the percentage of even-numbered digits, how many intervals (out of 30) would you expect not to capture 50%? Explain how you arrived at your answer.