Call me stupid but:
They think it flew faster for the same amount of time, but didn't travel as far!!
Does that sound right, or have they got something the wrong way round?
Previous answers to this question do not make sense either!
Let me try from dumbed down level that I am,
speed and distance are linear, speed and energy are non linear square law type of relationship.
another words if you increase your speed the distance travelled per unit of time will increase proportionally. But to get more speed you need a sh!t more go go juice, hence it runs out quicker, a lot quicker, hence you don't go as far.
Now theres heaps more in it than that from a aircraft viewpoint, but its morning and I'm still getting coffee