[UCANSEE2]

Think of it in terms of “time” and not “speed” and it will make sense.

But the question is about speed, and not time. Time is not in any of the givens. Time is a factor in determining MPH, but so is DISTANCE.

The issue is how you get AVERAGE MPH, not AVERAGE TIME.

Look at it this way:

IF I go 15mph for 1 mile, and 45mph for 1 mile, what is my average speed (mph) for a 2 mile course?

[BufordP]

1 mile * (1 hour / 15 miles)
+
1 mile * (1 hour / 45 miles)
=
time to travel 2 miles
--------- or ----------
1 mile * (3 hours/45 miles)
+
1 mile * (1 hour/45 miles)
=
4 hours miles/ 45 miles
-----------------------
2 miles = 4 hours / 45
= 2 miles * 45 / 4 hours
= 22.5 miles/hour