The director of admissions at a large university advises parents of incoming students about the cost...

The director of admissions at a large university advises parents of incoming students about the cost of textbooks during a typical semester. He selected a sample of 100 students and recorded their textbook expenses for the semester. He then calculated a sample mean of $675.60 and a sample standard deviation of $45.20. You may assume that the distribution of textbook expenses is approximately normally distributed.

(a) Is there sufficient evidence that the population mean textbook expense per semester is above $665? You should justify your answer with a hypothesis test at the 5% significance level.

(b) Construct a 95% confidence interval estimate of the population mean textbook expense per semester.

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orchestra answered 11 months ago

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