Let’s Make a Deal

The Friday File: Imagine having to choose one of three lotto tickets, two of which are worthless and one of which is valuable. Now suppose one of the two tickets not chosen is removed since the host knows it’s worthless. With two tickets left, what’s your best approach? Staying with the original or exchanging it for the other? Turns out selecting the other is optimal. It’s the Monty Hall Paradox.