CA 6 Confidence intervals – Solve problem #8.57 on page 261. http://www.youtube.com/watch?v=h2uhzcOFS2s Watch the above video and solve the problem on a Microsoft Excel worksheet and submit the MS Excel file and PDF on the Blackboard, prior to Midnight of the due date. 8.57. A random sample of small-business managers was given a leadership style questionnaire. The results were scaled so that each manager received a score for initiative. Suppose the following data are a random sample of these scores. 37 42 40 39 38 31 40 37 35 45 30 33 35 44 36 37 39 33 39 40 41 33 35 36 41 33 37 38 40 42 44 35 36 33 38 32 30 37 42 Assuming σ is 3.891, use these data to construct a 90% confidence interval to estimate the average score on initiative for all small-business managers. CA 7 Hypothesis testing - Z test – Solve problem #9.11 on page 284. http://www.youtube.com/watch?v=AvjJuCKUIq4 Watch the above video and solve the problem on a Microsoft Excel worksheet and submit the MS Excel file and PDF on the Blackboard, prior to Midnight of the due date. 9.11. According to HowtoAdvice.com, the average price charged to a customer to have a 12′ by 18′ wall-to-wall carpet shampoo cleaned is about $50. Suppose that a start-up carpet-cleaning company believes that in the region in which it operates, the average price for this service is higher. To test this hypothesis, the carpetcleaning company randomly contacts 23 customers who have recently had a 12′ by 18′ wall-to-wall carpet shampoo cleaned and asks the customers how much they were charged for the job. Suppose the resulting data are given below and that the population standard deviation price is $3.49. Use a 10% level of significance to test the hypothesis. Assume that such prices are normally distributed in the population. What is the observed value? What is the p-value? What is the decision? If the null hypothesis is rejected, is the result substantive? $52 52 56 50 50 51 49 49 54 51 51 48 56 52 52 53 56 52 52 56 57 48 53 CA 8 Hypothesis testing - t test – Solve problem #9.18 on page 290. http://www.youtube.com/watch?v=tdaVp9BOdjk Watch the above video and solve the problem on a Microsoft Excel worksheet and submit the MS Excel file and PDF on the Blackboard, prior to Midnight of the due date. 9.18. Suppose a study reports that the average price for a gallon of self-serve regular unleaded gasoline is $3.76. You believe that the figure is higher in your area of the country. You decide to test this claim for your part of the United States by randomly calling gasoline stations. Your random survey of 25 stations produces the following prices. $3.87 $3.89 $3.76 $3.80 $3.97 3.80 3.83 3.79 3.80 3.84 3.76 3.67 3.87 3.69 3.95 3.75 3.83 3.74 3.65 3.95 3.81 3.74 3.74 3.67 3.70 Assume gasoline prices for a region are normally distributed. Do the data you obtained provide enough evidence to reject the null hypothesis? Use a 1% level of significance. CA 9 Chi-square test – Goodness-of-fit test Solve the following problem: In the 2010 U.S. Census, the data for the ages of individuals in a small town were found to be the following: Percentage of Individuals Younger than 18 18-35 Older than 35 20% 30% 50% in 2019, ages of n=500 individuals from the same small town were sampled. Below are the results: Number of Individuals Younger than 18 18-35 Older than 35 121 288 91 Using alpha=.05, would you conclude that the population distribution of ages has changed in those 10 years? http://www.youtube.com/watch?v=offtAejQm_c&index=7&list=PLfG MkZaH76AkwGs1E1jHL3fZrc78sopeZ Watch the above video and solve the problem on a Microsoft Excel worksheet and submit the MS Excel file and PDF on the Blackboard, prior to Midnight of the due date. CA 10 Regression analysis – Solve problem #12.53 on page 468. http://www.youtube.com/watch?v=HIhdft8IyLU Watch the above video and solve the problem on a Microsoft Excel worksheet and submit the MS Excel file and PDF on the Blackboard, prior to Midnight of the due date. 12.53. Use the following data for parts (a) through (g). x 53 47 41 50 58 62 45 60 y 5 5 7 4 10 12 3 11 a. Determine the equation of the simple regression line to predict y from x. b. Using the x values, solve for the predicted values of y and the residuals. c. Solve for SSE. d. Calculate the standard error of the estimate. e. Determine the coefficient of determination. f. Test the slope of the regression line. Assume α = .05. What do you conclude about the slope? g. Comment on parts (d) and (e).
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