Ace the technical interview is riddled with inaccuracies (this has been covered here before.), but indeed this is one of the bigger howlers contained there-in.
Put simply,"It's not size that matters"!!. The number of track miles required for descent rely on the aircrafts Lift/Drag ratio and residual thrust/weight ratio, both of which are independent of size.
ATAPTQ is a good source of interview questions, but treat most of the answers given with healthy skepticism.