A biologist, a statistician and
A biologist, a statistician and a mathematician are on a photo-safari in africa. They drive out on the savannah in their jeep, stop and scout the horizon with their binoculars.
The biologist : “Look! There’s a herd of zebras! And there, in the middle : A white zebra! It’s fantastic ! There are white zebra’s ! We’ll be famous !”
The statistician : “It’s not significant. We only know there’s one white zebra.”
The mathematician : “Actually, we only know there exists a zebra, which is white on one side.”