Gasoline prices have been falling for about twelve months

Gasoline prices have been falling for about twelve months.  Because of this, the state transportation department wants to determine whether or not the mileage driven by motorists has increased from the historical average of 250 miles per week.  A sample of 100 motorists was taken to test the contention.  The average miles driven for these 100 motorists was 335 miles with a standard deviation of 500 miles.  Using a 5% significance level: a.         Set up the hypotheses, b.         What is the critical test statistic value? c.          calculate the test statistic.  d.         What is your conclusion?  Why?