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Problem of the Week 1127

A Tale of Two Sons

A woman has two children, not twins. One of them is a boy who was born on a Tuesday.

What is the probability that she has two boys?

Assume the basic boy-girl probability is 1/2. "One" means "at least one."

Source: Gary Foshee, seen on Ed Pegg's puzzle page, entry for Sept 7, 2009.

© Copyright 2009 Stan Wagon. Reproduced with permission.

17 November 2009