<p>It gives you the average speed, which, since it’s in miles per hour, and since the time is one hour, is also the distance. However, Xiggy’s point was that this formula, while necessary for a question that appears in the grid-in section, is not necessary.</p>
<p>Sample problem:</p>
<p>Bob drives from home to work and back. The trip takes him one hour. He averages 40mph there and 50mph. How far did he drive?</p>
<p>“How far did he drive” = distance traveled in one hour = average mph</p>
<p>a) 40
b) something around 44
c) 45
d) something around 46
e) 50</p>
<p>In this type of problem, the answer is ALWAYS slightly less than the average of the two speeds (40 and 50), ergo, the answer is b. Time to solve = 4 seconds. Just make sure you reread the question. I got one of these wrong on a practice test because the question was only asking for the distance one way. But then Adam Robinson yelled at me and made me reread the questions after I answer them.</p>