Chapter 12 q4 see attachment

A newI operating system is installed in every workstation at a large company. The claim cfthe 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 34 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 20.3 seconds with a standard deviation of 15 seconds. Complete parts a through d. a] What is the standard error of the mean difference? 55(8) =D (Round to Me decimal places as needed.) b] How many degrees offreedom does the t-statistic have? =1 c} What is the 95% condence interval for the mean dierence? (la) (Round to two decimal places as needed.) d) What do you conclude at a = 0.05? Choose the correct answer below. O A. Reject Ho since 0 is to the left of the confidence interval for the mean difference. There is sufficient evidence that the true mean difference is greater than 0. O B. Fail to reject Ho since 0 is not to the left of the confidence interval for the mean difference. There is sufficient evidence that the true mean difference is greater than 0. O C. Fail to reject Ho since 0 is not to the left of the confidence interval for the mean difference. There is not sufficient evidence that the true mean difference is greater than 0. O D. Reject Ho since 0 is to the left of the confidence interval for the mean difference. There is not sufficient evidence that the true mean difference is greater than 0