Mathematician answers are great aren't they?
-
A biologist, engineer and mathematician were having coffee on the patio.
Across the street they watch as two people walk into a house. A few minutes later, three people leave the house.
They start to discuss how that could happen.
Biologist: The two people copulated, reproduced and three people leave the house.
Engineer: That's wrong, our initial observation must have been erroneous.
Mathematician: You're both wrong. If another person enters the house it will be empty again.