[dba-Tech] The Three Doors Problem

I am the host of a TV program and you are the guest. This is the deal: there
are 3 doors. Behind one of them is $100 million. Behind the other two are a
dead catfish and a dead pickerel respectively. I invite you to select a
door. You choose any one of the three: call it x I open another door, and
say, Had you selected door y, you would have won a dead catfish. Now, would
you like to stick with your original choice or switch to the other door?
Does it matter? If not, why not? If so, why so?
There is a clear answer to this problem. Who is going to be the first to
come up with it?
Arthur