It is necessary for an automobile producer to estimate the number of miles per gallon (mpg) achieved by its cars. Suppose that the sample mean for a random sample of $40$ cars is $27.7$ mpg and assume the standard deviation is $3.2$ mpg. Now suppose the car producer wants to test the hypothesis that $\mu$, the mean number of miles per gallon, is $28.5$ against the alternative hypothesis that it is not $28.5$. Conduct a test using a significance level of $\alpha = .05$ by giving the following:

(a) The test statistic

(b) The P -value

(c) The final conclusion is

A. We can reject the null hypothesis that $\mu = 28.5$ and accept that $\mu \ne 28.5$.
B. There is not sufficient evidence to reject the null hypothesis that $\mu = 28.5$.