Question 450161: If I average 20 miles per hour on the way to a show and 30 miles per hour on the way back, what was my average speed for the entire trip?
You can put this solution on YOUR website! If I average 20 miles per hour on the way to a show and 30 miles per hour on the way back, what was my average speed for the entire trip?
------------
25 is not the average, because more time is spent going 20 mph than going 30.
Avg = 2*20*30/(20+30) = 24 mph
Suppose the distance from you to the show is 60 miles (we can choose such a number since the distances will all cancel out). Then, it takes 3 hours to get there and 2 hours to return back, so 5 hours total. You drove 120 miles total, so the average speed is 120 mi/5 hr = 24 mph.