Chapter 09 #1 of 4

Question 1 of 7 - /1 E ... View Policies Current Attempt in Progress Explain if the following is a two-tailed test, a left-tailed test, or a right-tailed test. Ho: M = 72, H1: M 80 O Ho: M = 135, H1: M View Policies Current Attempt in Progress If we set a = 0.0], what is the probability that we reject the null hypothesis when it was in fact true? The probability is Question 5 of 7 > - /1 ... View Policies Current Attempt in Progress Write the null and alternative hypotheses for the following example. Determine if the example is a case of a two-tailed, a left-tailed, or a right-tailed test. To test if the mean credit card debt of college seniors is less than 1000 dollars. O Ho: M=1000 dollars, H1: M> 1000 dollars, left-tailed test O Ho: M=1000 dollars, H1: M #1000 dollars, two-tailed test O Ho: M = 1000 dollars, H1: M 1000 dollars, right-tailed test O Ho: M=1000 dollars, H1: M - /1 ... Current Attempt in Progress (a) Indicate whether each of the following is a two-tailed test, a left-tailed test, or a right-tailed test. 1) Ho: M = 8, H1: W 8 is a v test. 3) Ho: M = 8, H1: 1 # 8 is a test. (b) Indicate the structure of the rejection region for each of the following hypothesis tests. 1) Ho: M = 8, H1: W 8. Rejection region is a 3) Ho: M = 8, H1: / # 8. Rejection region is a V.Question 7 of 7 - /1 E ... View Policies Current Attempt in Progress Define "Type I error." A Type I error is rejecting the null hypothesis when it is actually vand have been rejected.Question 1 of 5 i b) For a = 0.025, find the rejection region in terms of z. [Write your answer with 2 decimal places.] R : Z Zc) What test statistic corresponds to an x of 1.5 pounds? [Round your answer to 2 decimal places.] Z = i d) Should you reject the null hypothesis? VQuestion 2 of 5 51, n = 35, x = 57.5, o = 3.5, a = 0.02. We v Ho-Question 3 of 5 _ /'l :2 Current Attempt in Progress A random sample of 120 observations produced a sample mean of 29. Find the critical and observed values of z for the following test of hypothesis using a = 0.05. The population standard deviation is known to be 9 and the population distribution is normal. Hg: ,u = 28versus H1: ,u 7 28. Round your answers to two decimal places. zcritical left = zcritical right = zobserved = An 0.. Question4of5 _/1 i: View Policies Current Attempt in Progress A random sample of 107 observations produced a sample mean of 32. Find the critical and observed values of z for the following test of hypothesis using a = 0.05. The population standard deviation is known to be 8 and the population distribution is normal. H0: y = 28versus H1: ,u > 28. Round your answers to two decimal places. zcritical = zobserved = Question 5 of 5 - /1 E ... View Policies Current Attempt in Progress Define "Type I error." A Type I error is rejecting the null hypothesis when it is actually v and v have been rejected.0.. Question 2 of4 - H E View Policies Current Attempt in Progress The manufacturer of a certain brand of auto batteries claims that the mean life of these batteries is 45 months. A consumer protection agency that wants to check this claim took a random sample of 24 such batteries and found that the mean life for this sample is 43.05 months. The lives of all such batteries have a normal distribution with the population standard deviation of 4.5 months. Test the hypothesis H0: #5 = 45 months versus H1: ,u - /1 :: Lazurus Steel Corporation produces iron rods that are supposed to be 36 inches long. The machine that makes these rods does not produce each rod exactly 36 inches long. The lengths of the rods are normally distributed and vary slightly. It is known that when the machine is working properly, the mean length of the rods is 36 inches. The standard deviation of the lengths of all rods produced on this machine is always equal to 0.035 inch. The quality control department at the company takes a sample of 20 such rods every week, calculates the mean length of these rods, and tests the null hypothesis, ,1; = 36 inches, against the alternative hypothesis, u # 36 inches. lfthe null hypothesis is rejected, the machine is stopped and adjusted. A recent sample of 20 rods produced a mean length of 36.015 inches. Test the hypothesis H0: ,u = 36 inches versus H1: ,u :, 36 inches using the critical-value approach and a = 0.025. Does the machine need to be adjusted? Use the normal distribution table. The machine v adjustment. Question 4 of 4 - /1 ... View Policies Current Attempt in Progress A men's clothing store has been getting more requests for tall clothes, and the manager decides to see if the average customer is actually taller. From store records, he knows that the average height of customers five years ago was 71 inches. He randomly samples 20 customers over the next few days and finds that their average height is 72 inches, with a standard deviation of 3 inches. Is there evidence that this store's customers are taller than they were five years ago? (Use a = 0.05. )Question 1 of 7 - /1 E ... View Policies Current Attempt in Progress Perform the following test of hypothesis. Ho: M = 285, H1: M - /1 E ... View Policies Current Attempt in Progress Perform the following test of hypothesis. Ho: M = 10.70, H1: M # 10.70, n = 47, x = 12.146, s = 4.90, a = 0.01. Ho isQuestion 3 of7 _;1 :2 View Policies Current Attempt in Progress A company claims that its 8-ounce low-fat yogurt cups contain, on average, at most 150 calories per cu p. A consumer agency wanted to check whether or not this claim is true. A random sample of 10 such cups produced the following data on calories. 147 159 153 146 144 161 163 153 143 158 Test at the 10% signicance level whether the company's claim is true.Assume that the numbers of calories for such cups of yogurt produced by this company have an approximately normal distribution. Is company's claim true? 0.. Question 4 of 7 -/'I E View Policies Current Attempt in Progress Consider H0: ,u = 80 versus H1: u 72 80 forapopulation that is normally distributed. A random sample of 25 observations taken from this population produced a sample mean of 77 and a standard deviation of 7.6. Using a = 0.01 , would you reject the null hypothesis? .0. Question 5 of7 -/'I E View Policies Current Attempt in Progress The president of a university claims that the mean time spent partying by all students at this university is not more than 7 hours per week. A random sample of 40 students taken from this university showed that they spent an average of 8.30 hours partying the previous week with a standard deviation of 1.9 hours. Test at the 2.5% signicance level whether the president's claim is true. 0 The president's claim is false. 0 The president's claim is true. .0. Question 6 of7 _ [1 i: 0.. View Policies Current Attempt in Progress According to an estimate, 2 years ago the average age of all CEOs of medium- sized companies in the United States was 58 years. Jennifer wants to check if this is still true. She took a random sample of 70 such CEOs and found their mean age to be 53 years with a standard deviation of 6 years. Suppose that the probability of making a Type I error is selected to be zero. Can you conclude that the current mean age of all CEOs of medium-sized companies in the United States is different from 58 years? Question 7 of7