ASAP PLEASE Recall Exercise 9.23. Results essentially show that a sample of six quizzes was too small

for Anthony to claim that he is a stronger student. We realize that each student has his own

population of grades, with his own mean µi and variance σi^2. The observed quiz grades are sampled from this population, and they are different due to all the uncertainty and random factors involved when taking a quiz. Let us estimate the population parameters with some confidence.

Anthony says to Eric that he is a stronger student because his average grade for the first

six quizzes is higher. However, Eric replies that he is more stable because the variance of his

grades is lower. The actual scores of the two friends (presumably, independent and normally

distributed) are in the table.

Quiz 1 Quiz 2 Quiz 3 Quiz 4 Quiz 5 Quiz 6

Anthony 85 92 97 65 75 96

Eric 81 79 76 84 83 77

(a) Construct a 90% confidence interval for the population mean score for each student.

(b) Construct a 90% confidence interval for the difference of population means. If you have not completed Exercise 9.23(a), start by testing equality of variances and choosing the appropriate method.

(c) Construct a 90% confidence interval for the population variance of scores for each

student.

(d) Construct a 90% confidence interval for the ratio of population variances.