Super Duper Extra Hard Brainteaser
I'll open with a well know semi-easy one:
You know that a woman has exactly 2 children. You ask her if she has at least one girl, and she says yes. What's the probability that she has two girls?
Answer in white:
<font color="white"> 1/3 </font>
Now, suppose that 1% of all girls are named Sarah, and that if a mother had two girls that the mother would not name both of them Sarah
You know a woman has exactly 2 children, you ask her if she has a girl named Sarah, she says yes.
What are the chances she has two girls?
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