Based on information in Statistical Abstract of the United States (116 edition), the average annual miles driven per vehicle in the United States is 11.1 thousand miles, with @ = 600 miles. Suppose that a random sample of 39 vehicles owned by residents of Chicago showed that the average mileage driven last year was 10. thousand miles. Does this indicate that the average miles driven per vehicle in Chicago is different from (higher or lower than) the national average? Use a 0.05 level of significance. (a) What are we testing in this problem? a single proportion a single mean a difference of proportions a paired difference 7 a difference of means (b) What is the level of significance? State the null and alternate hypotheses (in thousands of miles). (Enter I= for as needed.)