1. For a fixed confidence level, when the sample size decreases, the length of the confidence interval for a population mean decreases. a. True b. False 2. The z score corresponding to a 95 percent confidence level is 2.10. a. True b. False 3. The larger the level of confidence, the shorter the confidence interval. a. True b. False 4. A 90% confidence interval for a population parameter means that if a large number of confidence intervals were constructed from repeated samples, then on average, 90% of these intervals would contain the true parameter. a. True b. False 5. As the sample size decreases, the confidence interval for the population mean will a. decrease b. increase c. stay the same d. decrease and then increase 6. You have measured the systolic blood pressure of a random sample of 25 employees of a company located near you. A 95% confidence interval for the mean systolic blood pressure for the employees of this company is (122, 138). Which of the following statements gives a valid interpretation of the confidence level? a. 95% of the sample of employees have a systolic blood pressure between 122 and 138. b. 95% of the population of employees have a systolic blood pressure between 122 and 138. c. If the procedure were repeated many times, 95% of the resulting confidence intervals would contain the population mean systolic blood pressure. d. The probability that the population mean blood pressure is between 122 and 138 is . 951 7. If the 98% confidence limits for the population mean are 73 and 80, which of the following could be the 95% confidence limits? a. 73 and 81 b. 72 and 79 c. 72 and 81 d. 74 and 79 e. none of these 8. To assess the precision of a laboratory scale, we measure a block known to have a mass of 1 gram. We measure the block n times and record the mean x of the measurements. Suppose the scale readings are normally distributed with unknown mean and standard deviation = 0.001 g. How large should n be so that a 95% confidence interval for has a margin of error of 0.0001? a. 20 b. 385 c. 10,000 d. 66,358 e. 384 9. The hypothesis being tested is the ______________. a. P-value b. Level of significance c. Null hypothesis d. Alternate hypothesis e. None of these 10. A t test is used instead of a z test because a. the population standard deviation is known. b. the population mean is known. c. the population mean is unknown. d. the population size is unknown. e. the population variance is unknown. f. None of these 11. The probability that we would get our observed result if the null hypothesis were true is the _______. a. P-value b. Level of significance c. Null hypothesis d. Alternate hypothesis e. None of these 12. The one-sample t statistic for a test of H0 : = 10 vs. Ha : < 10 based on n = 10 observations has a test statistic with the value t = 2.25. What is the p-value of this test? a. 0.974 b. 0.026 c. 0.051 d. 0.255 e. none of these 13. If the null hypothesis is rejected when it is true, a ______________ error has occurred. a. Power b. Type I c. Type II d. Type III e. None of these 14. A one-sided significance test gives a p-value of .04. From this we can a. Reject the null hypothesis with 99% confidence. b. Reject the null hypothesis with 96% confidence. c. Say that the probability that the null hypothesis is false is .04. d. Say that the probability that the null hypothesis is true is .04. e. None of these 15. Which of the following is not an assumption needed to perform a hypothesis test on a single mean using a z test statistic? a. An SRS of size n from the population. b. Known population standard deviation, . c. Either a normal population or a large sample (n 30). d. The population must be at least 10 times the size of the sample. e. All are needed