A car company says that the mean gas mileage for its luxury sedan is at least 21 miles per gallon (mpg). You believe the claim is incorrect and found that a random sample of 10 cars has a mean gas mileage of 20.6 mpg and a standard deviation of 4.5 mpg. Assume the gas mileage is normally distributed. At the 0.10 significance level, test the company's claim.
Find the test statistic and critical value. What would the Ho and Ha be? Would you reject or fail to reject the null hypothesis?