Concept: The question tests on TSD
Average speed over 2 equal distances travelled at speeds a and b is = 2aba+b2aba+b
If we get the speeds, we can find the average speed.
Statement 1: Morris drove from A to B at 40 miles per hour and returned back at 60 miles per hour.
We have the speeds over the 2 distances. We can find the average speed by the equation above.
Therefore Statement 1 Alone is Insufficient. Answer options could be A or D.
Statement 2:The distance between the towns A and B was 120 miles.
With this we cannot find the average speed.
Therefore Statement 2 Alone is Insufficient.