People (a) often think that it is unlikely that two individuals among 30 people will share a
birthday; (b) often think that more words begin with the letter “K” than have “K” in the
third letter position; and (c) often estimate that the Mississippi River is shorter if they first
answer if it is longer or shorter than 500 miles than if they first answer if it is longer or
shorter than 5000 miles. These ways of thinking reflect, in order, what heuristics?