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and many others in

"Chance Rules"

available below at amazon.co.uk

QHE Question:

and many others in

"Chance Rules"

available below at amazon.com

The Choise de Roi is a French term for having a boy first and then a girl. In his excellent book Chance Rules - An Informal Guide to Probability, Risk and Statistics , B Everitt gives an interesting account of these three situations, to which I have added another;

A new neighbour arrives at your door to borrow a cup of sugar. You ask whether she has any children. She replies (one of);

(a) "Yes I have two". "Any boys?", you ask.

(b) "Yes, one nine years old and one five". "Is the eldest a boy?", you ask.

(c) "Yes I have two" "Any boys?", you ask. "Yes" she says. The next day you see her with a small boy. "Is this your son?", you ask.

(d) "Yes". "Do you have two children?", you ask.

"Yes" she says, as she takes her sugar and leaves.
The question is, do these four possible answers affect the probability that both her children are boys? You should use this activity to write a few paragraphs about how the information given can alter the probability of an event.
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