Alex, Lizzie, Winnie, and Greg decided to randomly switch their four lunch boxes. If they each choose one of the four boxes at random, what is the probability that EXACTLY THREE of them end up with their original lunch box?
Well if three of them end up with the same lunch box and there are only 4 total lunch boxes, then that means all of them would get their original lunchbox.
For that to happen there is a 1/4 chance for each person to correctly pick their lunchboxes.
So it’s 1/4*1/4*1/4*1/4 and that equals to 1/256.
So there is a 1/256 chance that they will end up with their original lunch box.