AS I said, with such questions you must get to what is actually being asked...careful attention to this will raise your score on any IQ test. This is one reason they are limited, because some people realize this and others do not.
What is asked here is, given two point separated by two miles, if it takes 4 minutes to go halfway can you cover the entire distance in exactly 4 minutes? Obviously not since even at light speed you cannot cover the remaining mile in 0.0 minutes. You could get very close but that is not good enough :-) i.e 29.99999...Avg Mph
The time factor is implicit in the phrase “average speed” i.e to have an average speed of 30mph you must cover two miles in exactly 4 minutes.
BTW, tho other question, the one that stumped Einsteins friend was this. (it seems rather simple to me)
2.Comparing Discounts Which price is better for the buyer, a 40% discount or two successive discounts of 20%?
40% discount is better