Reference no: EM132300912

A large automobile manufacturer wanting to predict the CO2 emission for new vehicles ran an experimental group of 10 vehicles using an 85% ethanol-gasoline mixture. This mixture showed mean CO2 emissions of 240 pounds per 100 miles, with a standard deviation of 20 pounds. A control group of 14 vehicles using regular gasoline showed mean CO2 emissions of 252 pounds per 100 miles with a standard deviation of 15 pounds. At a = 0.05, in a left-tailed test (assuming equal variances) we conclude that the experimental ethanol-gasoline mixture

a) reduced the average CO2 emissions (close decision).

b) did not reduce the CO2 emissions (clear-cut decision).

c) reduced the average CO2 emissions (clear-cut decision).

d) did not reduce the CO2 emissions (close decision).