Does a fuel additive increase fuel efficiency? The fuel additive was added to full tanks of gasoline in m = 35 randomly selected vehicles. The vehicles were then each driven 100 miles and the mean fuel efficiency for these vehicles was calculated to be 1 = 37.2 miles per gallon with a standard deviation of s = 4.2 miles per gallon. A second sample of 72 = 42 randomly selected vehicles had their gas tanks filled without the fuel additive. These vehicles were then each driven 100 miles and the mean fuel efficiency for these vehicles was calculated to be 2 = 31.5 miles per gallon with a standard deviation of s = 6.7 miles per gallon. Calculate an 85% confidence interval. You may assume the conditions have been met O (4.4, 7.0) O (5.1, 6.2) O None of the above O (3.9, 7.5)