A special bumper was installed on selected vehicles in a large fleet. The dollar cost of body repairs was recorded for all vehicles that were involved in accidents over a 1-year period. Those with the special bumper are the test group and the other vehicles are the control group, shown below. Each "repair incident" is defined as an invoice (which might include more than one separate type of damage).

A special bumper was installed on selected vehicles in a large fleet. The dollar cost of body repairs was recorded for all vehicles that were involved in accidents over a 1year period, Those with the special bumper are the test group and the other vehicles are the control group, shown below. Each "repair incident" is defined as an invoice (which might include more than one separate type of damage). Statistic __ Test Group (Lolitrol Group Mean Damage X1 : $ 1,073 X2 : $ 1,723 Sample Std. Dev. 31 : 3 664 S2 : S 816 Repair Incidents n1 2 11 [12 = 9 Source: Unpublished study by Thomas W. Lauer and Floyd G. Willoughby. (8) Construct a 95 percent confidence interval for the true difference of the means assuming equal variances. (Round your intermediate tcrit value to 3 decimal places. Round your final answers to 3 decimal places. Negative values should be indicated by a minus sign.) The 95% confidence interval is from 4344.476 0 to 44.476 0 (b) Repeat part (a), using the assumption of unequal variances with Welch's formula for df (Round your intermediate tcrit value to 3 decimal places. Round your final answers to 3 decimal places. Negative values should be indicated by a minus sign.) The 95% confidence interval is from |:| to Cl (c) Did the assumption about variances change the conclusion? Yes N00