Three people are in a hot-air balloon. Soon, they find themselves lost in a canyon somewhere. One of the men says, "I've got an idea. We can call for help in this canyon and the echo will carry our voices far."
So he leans over the basket and yells out, "Helllloooooo! Where are we?" (They hear the echo several times).
Fifteen minutes later, they hear this echoing female voice: "Helllloooooo! You're lost!!"
One of the three says, "That must have been a mathematician."
Puzzled, one of the men asks, "Why do you say that?"
The reply: "For three reasons:
- She took a long time to answer
- She was absolutely correct, and
- Her answer was absolutely useless."