8. For a test of a mean, which of the following is incorrect? a) Ho is rejected when the calculated value is less than the critical value of the test statistic (if both positive). b) In a right-tailed test (rejection region on the high (values larger than the mean) side), we reject H, when the test statistic exceeds the critical value. c) The critical value is based on the researcher's chosen level of significance. d) If Ho: u 100 and H1: > 100, then the test is right-tailed. 9. Hypothesis tests for a mean using the critical value method require: a) using a two-tailed test. b) sampling a normal population. c) knowing the true population mean. d) specifying a in advance. 10. Which is not a likely reason to choose the z distribution for a hypothesis test of a mean? a) The value of o is known. b) The sample size n is very large. c) The population is normal. d) The value of o is very large.