During a test period,an experimental group of 10 vehicles using an 85 percent ethanol-gasoline mixture showed mean CO2 emissions of 667 pounds per 1000 miles,with a standard deviation of 20 pounds.A control group of 14 vehicles using regular gasoline showed mean CO2 emissions of 679 pounds per 1000 miles with a standard deviation of 15 pounds.At α = .05,in a left-tailed test (assuming equal variances)the test statistic is
A)−1.310
B)−2.042
C)−1.645
D)−1.683

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The Answer of During a test period,an experimental group of 10 vehicles using an 85 percent ethanol-gasoline mixture showed mean CO2 emissions of 667 pounds per 1000 miles,with a standard deviation of 20 pounds.A control group of 14 vehicles using regular gasoline showed mean CO2 emissions of 679 pounds per 1000 miles with a standard deviation of 15 pounds.At α = .05,in a left-tailed test (assuming equal variances)the test statistic is
A)−1.310
B)−2.042
C)−1.645
D)−1.683

During a Test Period,an Experimental Group of 10 Vehicles Using