A college bookstore tells prospective students that the average cost of its text

Question

A college bookstore tells prospective students that the average cost of its textbooks is $72. A group of skeptical statistics students from the school thinks that the average cost is higher. In order to test the bookstore’s claim, the students will select a random sample of size n= 80 books.  The mean from their random sample (x-bar) is $76.50 and standard deviation is $6.00. 

a.)  (4 points)  In your Excel file, state the appropriate null (H0) and alternative (Ha) hypotheses.  You can write "Mu" for the population mean. 

b.)  (4 points)  In your Excel file, calculate the test statistic, or z-score, for the test. 

c.)  (4 points)  In your Excel file, use either a rejection region approach or a p-value approach to conclude on your test.  State your conclusion statistically (reject or fail-to-reject Ho) and then restate the conclusion in terms of the actual problem. 

Explanation / Answer

Ho : miu = 72

Ha : miu > 72

Z = ( 76.50 - 72 ) / ( 6 / srqt80 )

Z = 6.71

p value : 0.0000

since p value is lower than alpha ( 0.05) we reject Ho

conclusion

there is sufficeint evidence to support the claim that average cost is hihger than 72

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