ABSTRACT
This paradox simply illustrates popular confusion about probability, and perhaps would not be worth including if it were not for the fact that even some academic mathematicians, among them the great number theorist Paul Erdo´´s, at first vehemently refused to accept that swapping was advantageous. After all, either the other unopened door conceals the prize or the one first picked does. Doesn’t that make it equally likely that either of those two doors has the prize behind it?
