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Some manufacturers claim that non-hybrid sedan cars have a lower mean miles-per—gallon (mpg) than hybrid ones

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Some manufacturers claim that non-hybrid sedan cars have a lower mean miles-per—gallon (mpg) than hybrid ones. Suppose that consumers test 21 hybrid sedans and get a mean of 25 mpg with a standard deviation of seven mpg. Thirty-one non-hybrid sedans get a mean of 23 mpg with a standard deviation of four mpg. Suppose that the population standard deviations are known to be seven and three, respectively. Conduct a hypothesis test to evaluate the manufacturers' claim. Test at a 1% level of significance

What is the p-value?