1. Test Ho: µ =100; H1: µ < 100, using n = 36 and alpha = .05 If the sample mean = 95 and the sample standard deviation = 10, which of the following is true?
- A. test statistic = -3.00; critical value = -1.69; we fail to reject Ho.
- B. test statistic = -3.00; critical value = -1.69; we reject Ho and accept H1.
- C. test statistic = 3.00; critical value = 1.69; we reject Ho.
- D. None of these answers are correct.
2. Assume that the population variance is unknown. We test the hypothesis that Ho: µ=5 against the alternative that it is not at a level of significance of 5% and a sample size of n=151. We calculate a test statistic = -1.976. The p-value of this hypothesis test is approximately
3. A taxi company is interested in the amount of time its vehicles are out of operation for repair. Find a 95% confidence interval for the mean number of days in a month that all taxis are out of operation for repair. A random sample of nine taxis had the following number of days that each was in repair (Note that we are using sample data and must estimate the sample standard deviation using the sample formula.):
10 16 19 14 19 21 22 8 17
4. A professor found that the historical scores on on the final exams follow a normal distribution with a A random sample of nine test scores from the current class had a mean score of 187.9 points and a sample standard deviation of 32.4 points. Find the 98% confidence interval for the population mean score of the current class.