Question 7 options: A manager evaluates effectiveness of a major hardware upgrade by running a certain process 40 times before the upgrade and 50 times after the upgrade. Based on these data, the average running time is 12 minutes before the upgrade, 8 minutes after it. Historically, the standard deviation has been 1.6 minutes, and presumably it has not changed. Construct a 95% confidence interval [a, b] showing how much the running time reduced due to the hardware upgrade. Round your answers to 2 decimal places