During an orientation event at a large university, incoming students are advised about the cost of
textbooks for a typical study period. A sample of 100 students currently enrolled at this university
indicates a sample mean cost of $315.40. A population standard deviation is known to be $43.20.
(a) (8 marks) Construct a 95% confidence interval for the true population mean cost of textbooks.
Explain what the values you have calculated mean. Provide a diagram (a template is available on the
course website) to assist in your explanation.
(b) (3 marks) Does the population cost of textbooks have to be normally distributed here? Explain
(c) (5 marks) Suppose that the campus newspaper previously claimed that the average cost of
textbooks was $300 per study period. If the campus newspaper’s claim were still true, what would be
the probability, in a sample of 100 students, of a mean cost of textbooks above $310?