The right answer. Can you list the three scenarios? I think it is easier to list nine scenarios.
Nine?!
Say box one is the box the the Mather in:
You pick box 1 : change your pick and you loose, keep your pick and you win
You pick box 2: change you pick and you win, keep your pick you loose
Pick box 3: change you pick and you win, keep your pick you loose
Nine?!
Say box one is the box the the Mather in:
You pick box 1 : change your pick and you loose, keep your pick and you win
You pick box 2: change you pick and you win, keep your pick you loose
Pick box 3: change you pick and you win, keep your pick you loose