From: Eliezer S. Yudkowsky (sentience@pobox.com)
Date: Mon Mar 24 2003 - 22:34:00 MST
Here's a brainteaser I invented lately. Suppose you have a large barrel
containing a number of plastic eggs. Some eggs contain pearls, the rest
contain nothing. Some eggs are painted blue, the rest are painted red.
Suppose that 40% of the eggs are painted blue, 5/13 of the eggs containing
pearls are painted blue, and 20% of the eggs are both empty and painted
red. What is the probability that an egg painted blue contains a pearl?
As a check on your results: The proportion of red eggs which are empty,
divided by the proportion of all eggs containing pearls, is approximately
.51. To use this information in the problem would, of course, be cheating.
-- Eliezer S. Yudkowsky http://singinst.org/ Research Fellow, Singularity Institute for Artificial Intelligence
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