Question 28 A website that rents movies online recorded the age and the number of movies rented during the past month for some of their customers. The data are shown below for a random sample of 24 of their customers. The regression line for the data, with number of movie rentals as the response variable, provides an intercept = 18.08, and slope = -0.254. One of the data points was for a 20-year-old customer who had rented 15 movies. The residual value for this customer is: 5.73 6.89 1.28 -6.89 Question 29 A random sample of 29 observations from a normal population provides sample mean = 87, and sample standard deviation = 30. The standard error of the sample mean is equal to: 5.57 3 0 16.16 30 Question 30 A new operating system is installed in every workstation at a large company. The claim of the operating system manufacturer is that the time to shut down and turn on the machine will be much faster. To test it an employee selects 23 machines and tests the combined shut down and restart time of each machine before and after the new operating system has been installed. The mean of the differences (before - after) is 18.5 seconds with a standard deviation of 15.6 seconds. The standard error of the mean time difference is: 3.11 3.25 00 4.45 6.09 Question 31 For obtaining a 98% Confidence Interval for the difference of the means of two normal populations, two random samples, one from each population, both of the same size 13, were drawn. For the first sample, sample mean = 28, and sample standard deviaiton = 5.56. For the second sample, sample mean = 20, and sample standard deviation = 12.36. Assuming unequal variances for the two populations, the standard error SE for the difference of the sample means is: 6.384 14.129 0 4.899 3.759 Question 32 Partial Excel output from another random sample of 10 observations Multiple R R Square Regression Statistics Adjusted R Square Standard Error Observations ANOVA Regression Residual Total df SS MS F Significance F 230.8 350.4 Coefficients Standard Error t Stat P-value Intercept 9.795 3.508 Number of salespeople working (x) 0.681 0.319 The Standard Error Se is equal to (rounded to three places of decimal): 5.362 Lower 95% Upper 95%