[EX09-153] The total cost of required textbooks for nine freshman- or sophomore-level classes at 10 randomly selected New York private colleges was collected: 639.00 865.75 868.20 874.25 887.06 890.50 970.13 1013.22 1026.00 1048.96

a. Construct a histogram and find the mean and standard deviation.

b. Demonstrate how this set of data satisfies the assumptions for inference.

c. Find the 95% confidence interval for , the mean total cost of required textbooks.

d. Interpret the meaning of the confidence interval.

e. Is there a difference in the mean total cost of the nine required textbooks between the public colleges in Exercise 9.152 and in the private colleges in this exercise? Explain.

f. Explain why the confidence interval for the public colleges is so much wider than the corresponding interval for the private colleges. Be exact and detailed.