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

Multiple Choice

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.Assuming equal variances,the pooled variance is

A) 296.59
B) 225.00
C) 400.00
D) 522.16