You run a publishing company and you are assessing your proofreaders. You hope that they can proofread an average of 1000 words per hour, an industry benchmark, If they average fewer than 1000 words per hour you will need to reconfigure the staffing. You test the proofreading times of a sample of 100 of the proofreaders and find the sample average words per hour is 975 and the sample standard deviation is s 600. Test whether the population mean words per hour is greater than 1000 with a 95% confidence level. The z-critical value for this test is za Z0.05 = 1.645. Show all your steps clearly and illustrate your answer with a graph.

If the mean snowfall for Ottawa Ontario Canada is 98 inches per year and the standard deviation is 25 inches what percentage of the time does Ottawa receive less than 125 inches of snow?

One personality test available on the World Wide Web has a subsection designed to assess the "honesty" of the test-taker. After taking the test and seeing your score for this subsection, you're interested in the mean score, µ, among the general population on this subsection. The website reports that µ is 142, but you believe that u is less than 142. You decide to do a statistical test. You choose a random sample of people and have them take the personality test. You find that their mean score on the subsection is 135 and that the standard deviation of their scores is 28. Based on this information, answer the questions below. What are the null hypothesis (H) and the alternative hypothesis (H,) that should be used for the test? Ho: u is ? ? |H,: µ is ? H : ? In the context of this test, what is a Type II error? A Type II error is ? v the hypothesis that u is ? v when, in fact, μ is| ? ? Suppose that you decide not to reject the null hypothesis. What sort of error might you be making? ?

An article in a local town newspaper discusses the results of state test scores in their town. The reporter headlines, "The students in this town don't have the necessary skills.  The overall student population is less than what is reported at the state level" The state test says that a score of 261 or higher on its test reflects the student has the skills needed to graduate. A local town newspaper conducted a random sample of 200 students and found the mean to be 257 and a standard deviation of 41 points. a. State the null (H0) and alternative (Ha) hypotheses. b. Give the standard score for the data. c. Find the P-value for this significance test. e. Sketch your results on the standard Normal distribution f. Summarize the conclusion in the context of this problem.

One personality test available on the World Wide Web has a subsection designed to assess the "honesty" of the test-taker. After taking the test and seeing your score for this subsection, you're interested in the mean score, µ, among the general population on this subsection. The website reports that u is 148, but you believe that u is greater than 148. You decide to do a statistical test. You choose a random sample of people and have them take the personality test. You find that their mean score on the subsection is 155 and that the standard deviation of their scores is 28. Based on this information, answer the questions below. What are the null hypothesis (H,) and the alternative hypothesis (H,) that should be used for the test? H: u is ? |H;: µ is ? ? In the context of this test, what is a Type I error? A Type I error is ? fact, u is ? v the hypothesis that u is ? v? v. when, in Suppose that you decide to reject the null hypothesis. What sort of error might you be making? ?

Prof. Torres took her dog Manzy for a walk for 6 days.  These are the number of minutes of each of the 6 days. (Round to hundredths, if needed).  5, 25, 60, 25, 25, 50   What is the mean? What is the sum of squares? What is the sample variance ? What is the sample standard deviation?

Two friends, Karen and Jodi, work different shifts for the same ambulance service. They wonder if the different shifts average different numbers of calls. Looking at past records, Karen determines from a random sample of 40 shifts that she had a mean of 5.1 calls per shift. She knows that the population standard deviation for her shift is 1.2 calls. Jodi calculates from a random sample of 31 shifts that her mean was 5.8 calls per shift. She knows that the population standard deviation for her shift is 1.4 calls. Test the claim that there is a difference between the mean numbers of calls for the two shifts at the 0.01 level of significance. Let Karen's shifts be Population 1 and let Jodi's shifts be Population 2.   Step 3 of 3 :   Draw a conclusion and interpret the decision.