An online computer support company claims that their mean call-back time is less than 30 minutes. A random sample of 36 calls has a sample meanx= 28.5 minutes and a sample standard deviation s of 3.5 minutes. Choose the expression that calculates the test statistic t for the hypothesis test that tests the company's claim.

28.530

3.5

36

28.530

(3.5)²

36

3028.5

3.5

36

28.530

3.5

36

3028.5

3.5

36