James Tauber's Blog 2008/04/17


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Barry and Frank

Continuing on from the previous Barry and Frank story...

Colin comes up to Barry and Frank and says "I've just tossed this coin 100 times and recorded the result each time in this notebook. What is the probability that toss number 37 was tails?". Frank thought for a moment and asked "can we study the notebook?" "Sure," Colin said.

Frank took the notebook and looked through it before declaring "well, 40 out of 100 tosses were tails, so the probability of toss number 37 having been tails is 0.4".

"I agree," said Barry, somewhat to the surprise of Frank. But Barry then took the notebook, turned to the appropriate entry and said "oh, the probability just changed to 1"

by : Created on April 17, 2008 : Last modified April 17, 2008 : (permalink)