Let’s consider another variation of the four-doors problem. say the doors are labeled a, b, c, and d. suppose that carol always opens the earliest door possible (the door whose label is earliest in the alphabet) with the restriction that she can neither reveal the prize nor open the door that the player picked. this gives contestant mergatroid— an engineering student from cambridge, ma— just a little more information about the location of the prize. suppose that mergatroid always switches to the earliest door, excluding his initial pick and the one carol opened. what is the probability that he wins the prize?