From Freedmans statistics, page 165, Regression, Exercise Set D.
Answer : "Well under 50% - the regression effect"
I'm not sure about the reasoning for this though, I'm not sure I really follow what the question is asking either.
They haven't said that there's any relation or whatever between education and income for this question, though the way it's setup I'm thinking that they're assuming something like this :
I'm told that we're referring to people in the 90th percentile of education, so that would be the blue part of this graph (?) :
I'm not sure how to reason about income based on this, with respect to the education level and this question .
I'm not sure if the graphs that I've provided are helpful or not either.