Question

true or false

11. When the level of confidence and the sample size remain the same, a confidence interval for a population mean y will be narrower, when the sample standard deviation s is smaller than when s is larger. Chapter 10 12. The closer is the hypothesized mean is from the actual mean the higher is the power of the test. 13. The manager of the quality department for a tire manufacturing company wants to know the average tensile strength of rubber used in making a certain brand of radial tire. She knows the population standard deviation and uses a Z test to test the null hypothesis that the mean tensile strength is 800 pounds per square inch. The calculated Z test statistic is a positive value that leads to a p-value of .067 for the test. If the significance level is .01, the null hypothesis would be rejected. Assume that the population of pressure values is normally distributed. 14. The smaller the p-value, the more we doubt the null hypothesis. 15. You cannot make a Type II error when the null hypothesis is true. 16. Type I error is failing to reject a False Null Hypothesis.

Answer 1

11) The said statement is true.when the level of confidence and sample so remains the same , confidence interval for the population mean will be narrower, when the sample standard deviation s is smaller than when s is larger.

12) The said statement is true. The closer is the hypothesised mean from the actual mean , higher is the power of the test.

14)Null hypothesis is a statement in which there is no relationship between two variables. In statistics ,p- value means the probability of obtaining the observed result of a test,assuming that the null hypothesis is correct.A smaller p- value means that there is stronger evidence in favor of the alternative hypothesis.Therefore when smaller the p_ value,there is strong evidence in favor of alternative hypothesis and not null hypothesis.so the said statement is true.

15) Type two error is the non rejection of false null hypothesis.when the null hypothesis is false and you fail to reject it,you make a type two error.Therefore the said statement is true

16) Type one error is the rejection of a true null hypothesis.Therefore the said statement is true.