[EX09-034] College students throw out an average of 640 lb of trash each year, 30% of that in the month before graduation according to the June 2004 Readers Digest article “Campus Castoffs.” Last year, 20 universities raised more than $100,000 for local charities by selling the “junk.” To estimate the amount of trash discarded by the students at State University, 18 students were randomly selected and carefully monitored for 1 year. The amounts of trash discarded (in pounds) were as follows:

692 563 482 413 437 456 509 347 676 944 678 392 399 742 584 492 514 758

a. Describe the data using a histogram and its mean and standard deviation.

b. Determine whether an assumption of normality is reasonable. Explain.

c. Construct a 95% confidence interval for the mean amount of trash.

d. What does the confidence interval suggest about the mean amount of trash discarded by the students at State University compared with that discarded by all college students.