QMB FINAL EXAM 2 with complete solution Graded A,latest update.

QMB FINAL EXAM 2 Question 1 1. For a given hypothesis test, if we do not reject H0, and H0 is true. Answer No error has been committed. Type I error has been committed. Type II error has been commi ...

QMB FINAL EXAM 2 Question 1 1. For a given hypothesis test, if we do not reject H0, and H0 is true. Answer No error has been committed. Type I error has been committed. Type II error has been committed. Type III error has been committed. 4 points Question 2 1. When the margin of error is added to and subtracted from the sample mean an interval is formed that will contain m with probability of (1 - a). Answer True False 4 points Question 3 1. The following list represents a sample of the ages of the soldiers enlisting in the military: 19, 22, 23, 19, 21, 22, 19, 23, 21. Assume that the population standard deviation is known to be 2 years. Construct a 99% confidence interval for the average age of the soldier enlisting in the military. Answer 17.92 to 24. 08 15.85 to 26.15 18.76 to 23.24 19.28 to 22.72 19.42 to 22.58 4 points Question 4 1. For the following hypothesis test where H0: µ ≤ 10 vs. Ha: µ > 10, we reject H0 at level of significance α and conclude that the true mean is greater than 10 when the true mean is really 8. Based on this information we can state that we have: Answer Made a Type I error Made a Type II error Made a correct decision Increased the power of the test 4 points Question 5 1. First a 90% confidence interval is constructed from a sample size of 100. Then, for the same identical data, a 92% confidence interval is constructed. The width of the 90% interval is wider than the 92% confidence interval. Answer True False 4 points Question 6 1. When comparing two population means based on independent random samples, the pooled estimate of the variance is used if both population standard deviations are known. Answer True False 4 points Question 7 1. For the following hypothesis test where H0: µ ≤ 10 vs. Ha: µ > 10, we reject H0 at level of significance α and conclude that the true mean is greater than 10 when the true mean is really 14. Based on this information we can state that we have: Answer Made a Type I error Made a Type II error Made a correct decision Increased the power of the test 4 points Question 8 1. In a manufacturing process a random sample of 9 bolts manufactured has a mean length of 3 inches with a variance of .09. What is the 90% confidence interval for the true mean length of the bolt? Answer 2.8355 to 3.1645 2.5065 to 3.4935 2.4420 to 3.5580 2.8140 to 3.1860 2.9442 to 3.0558 4 points Question 9 1. Which of the following assumptions are necessary in testing the difference between the means of two normally distributed populations using large independent random samples? Answer Both sample populations are normally distributed. Both samples are independently selected. Both samples are randomly selected. B and C only A, B, and C 4 points Question 10 1. When comparing two independent population means, if n1 = 13 and n2 = 10, degrees of freedom for the t statistic is 22. Answer True False 4 points Question 11 1. The average customer waiting time at a fast food restaurant has been 7.5 minutes. The customer waiting time has a normal distribution. The manager claims that the use of a new system will decrease average customer waiting time in the store. What is the null and alternative hypothesis for this scenario? Answer H0: µ = 7.5 and HA ≠ 7.5 H0: µ ≤ 7.5 and HA> 7.5 H0:µ ≥ 7.5 and HA < 7.5 H0: µ > 7.5 and HA ≥ 7.5 H0: ≤ > 7.5 and HA = 7.5 4 points Question 12 1. In testing for the equality of means from two independent populations, if the null hypothesis is false, the test could result in: Answer A Type I error. Either a Type I error or a Type II error. Neither a Type I error or a Type II error. A Type II error. Both a Type I error and a Type II error. 4 points Question 13 1. As the level of significance α increases, we are more likely to reject the null hypothesis. Answer True False 4 points Question 14 1. What value(s) of alpha would we reject H0 for µ greater than the mean 10 if µ = 11, s = 2, and n = 36? Answer .05 and .01 .01 and .001 .001 All of the above 4 points Question 15 1. When the null hypothesis is not rejected, there is no possibility of making a Type I error. Answer True False 4 points Question 16 1. The null hypothesis is a statement that will be accepted only if there is convincing sample evidence that it is true. Answer True False 4 points Question 17 1. A confidence interval increases in width as Answer The level of confidence increases n decreases s increases All of the above 4 points Question 18 1. In order to test the effectiveness of a drug called XZR designed to reduce cholesterol levels, 9 heart patients' cholesterol levels are measured before they are given the drug. The same 9 patients use XZR for two continuous months. After two months of continuous use the 9 patients' cholesterol levels are measured again. The comparison of cholesterol levels before vs. after administering the drug is an example of testing the difference between: Answer Two population means from independent populations. Two sample means from independent populations. Matched pairs from two dependent populations. 4 points Question 19 1. Which statement is incorrect? Answer The null hypothesis contains the equality sign. When a false null hypothesis is not rejected, a Type II error has occurred. If the null hypothesis is rejected, it is concluded that the alternative hypothesis is true. If we fail to reject the null hypothesis, then it is proven that null hypothesis is true. 4 points Question 20 1. When the level of confidence and the sample size remain the same, a confidence interval for a population mean μ will be wider, when the sample standard deviation σ is small than when σ is large. Answer True False 4 points Question 21 1. If a one-sided null hypothesis for a single mean cannot be rejected at a given significance level, then the corresponding two-sided null hypothesis (i.e., the same sample size, the same standard deviation, and the same mean) will_________ be rejected at the same significance level. Answer Always Sometimes Never 4 points Question 22 1. If a two-sided null hypothesis is rejected for a single mean at a given significance level, the corresponding one- sided null hypothesis (i.e., the same sample size, the same standard deviation, and the same mean) will_________ be rejected at the same significance level. Answer Always Sometimes Never 4 points Question 23 1. Which of the following is not an assumption for one-way analysis of variance? Answer The p populations of values of the response variable associated with the treatments have equal variances. The samples of experimental units associated with the treatments are randomly selected. The experimental units associated with the treatments are independent samples. The number of sampled observations must be equal for all p treatments. The distribution of the response variable is normal for all treatments. 4 points Question 24 1. Alpha (α) is the probability that the test statistic would assume a value as or more extreme than the observed value of the test. Answer True False 4 points Question 25 1. When the population is normally distributed, population standard deviation σ is unknown, and the sample size is n = 15; the confidence interval for the population mean µ is based on: Answer The z (normal) distribution The t distribution The Binomial distribution The Poisson Distribution None of the above