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**Fruityloop****Member**- Registered: 2009-05-18
- Posts: 139

This is from a book. There are 2 graves. You know that at least one of the graves contains the body of a woman. If you randomly select one of the graves and exhume the body, what is the probability that it will be a woman? The book gives the probability as 3/4. I thought that the answer in the book was wrong and should be 2/3. I have come to the conclusion that the book is correct after all and the correct answer is 3/4.

*Last edited by Fruityloop (2020-06-14 15:04:56)*

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**renevanderlende****Member**- From: The Netherlands
- Registered: 2020-01-06
- Posts: 28

Purely on intuition: the chance that you'll find a woman is twice the probability you find a man: two graves => might be 2 women. So 2 women and 1 man would yield 2/3 chance you will find a woman. This is because you know that there will at least be a woman in one of the graves. Without that knowledge it would be 50/50.

Shred that book...

*Last edited by renevanderlende (2020-03-25 15:40:29)*

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**Bob****Administrator**- Registered: 2010-06-20
- Posts: 8,914

hi Fruityloop

There's a useful tool that will help here. It's called a tree diagram.

So don't throw the book yet. But there's plenty of ways of setting up this problem without exhuming graves. I think the author needs psychiatric help.

Bob

Children are not defined by school ...........The Fonz

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

Sometimes I deliberately make mistakes, just to test you! …………….Bob

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**renevanderlende****Member**- From: The Netherlands
- Registered: 2020-01-06
- Posts: 28

Wadda ya know, scored myself another F. Hope you've got glue, Fruityloop....

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