26 Formulate the null and alternative hypothesis in each cas

26. Formulate the null and alternative hypothesis in each case:

a. Ten years ago the average American drank 2.5 cups of coffee per day. You suspect that amount has changed since then.

b. A researcher at Ohio State University speculates that the average SAT score for entering freshmen is higher than the national average of 1,650.

c. The manager of the University of Iowa bookstore suspects the average amount of money a student spends on books is less than the reported $400.

Solution

Note that suspicions/claims go to the alternative hypothesis, and the opposite if it is the null hypothesis:

a)

Ho: u = 2.5
Ha: u =/= 2.5

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b)

Ho: u <= 1650
Ha: u > 1650

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c)

Ho: u >= 400
Ha: u < 400