An experiment was conducted in order to evaluate the effectiveness of two devices for improving the efficiency of car engine systems. Engine efficacy was measured after one of the two devices was fixed. The two devices were an electric vent-200F (200F) and electric vent-149S (149S). The Engine efficacy data (BTU.In) are stacked in one column with a grouping column (Vent-type) containing identifiers or subscripts to denote the population. See attached excel file on tab (car_engine) Suppose that you performed a variance test and found no evidence for variances being unequal -Test the normality assumption (by graph and goodness of fit) and Show your work using confidence interval and hypothesis testing procedures to test the variances equality- (software + manual) Now you want to compare the effectiveness of these two devices by determining whether or not there is any evidence that the difference between the devices is different from zero. - (software + manual)