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A probability Mess

Bob had to pick one of the three boxes lying on the table. If he wished to select them with equal probability, how could he do it by using a penny in his pocket? What if the penny was biased?

Deepak pant(STM)
Friday, June 17, 2005

unbiased penny
single flip: 1 = head, 0 = tail
do it twice

00 = box 1
01 = box 2
10 = box 3
11 = repeat until not 11

biased penny
double flip: 1 = head then tail, 0 = tail then head, head head or tail tail are invalid double flips
get two valid double flips

00 = box 1
01 = box 2
10 = box 3
11 = repeat until not 11

j
Saturday, June 18, 2005

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