Tens of thousands of people die each year on America's highways. How can the number of fatalities be reduced? In this question we explore trends in traffic fatalities across the 50 states and potential solutions to the problem. Consider the table below, indicating summary statistics of the number of traffic deaths per million miles driven across all 50 states, in 1985 and 1992. (Assume that these observations represent random samples of all years.)

Variable | Obs Mean Std. Dev. Min Max

---------------+--------------------------------------------------------

traffic_1985 | 50 2.694 .6079104 1.9 4.4

traffic_1992 | 50 1.844 .449108 1 2.7

1. [2 points] What is the average change (the difference in averages) across states between 1985 and 1992 in traffic deaths per million miles driven?
2. [2 points] How likely would we get the average change found in part a) if the true difference in the population were actually zero? Show your work.
3. [2 points] Can we reasonably claim that there is a difference in traffic fatalities between 1985 and 1992? (Again, the samples can be treated as random.) Explain.