So you thought Monty Hall was tricky?

[MrsLime]

Ok, maybe algebra was a bad idea.  How about:

Snoopy opens the envelope and finds £20.  I.e. the envelope definitely contains £20!  He thinks to himself: "Great I have £20, but... there is a 50% chance that Danafish's envelope contains £10, and 50% that Danafish's envelope contains £40.  So if I swap envelopes, 50% of the time I lose £10 and 50% I gain £20.  So, on average, I gain £5 by swapping.  Therefore I should swap!"

Now where is the flaw?

(BTW, I don't know the answer, I am trying to understand as well.)

[roverthtaeh]

Both people think they gain by swapping. Agreed.
Here's my philosophy:
The other guy wants to swap because he thinks he'll gain.
So I refuse to swap, therefore I gain what he thought he would gain.
And if I'm wrong, he goes "neener neener" and sticks his tongue out.
But I'm financially better off than I was 5 minutes ago, so who cares.

[MrsLime]

Both people think they gain by swapping. Agreed.
Here's my philosophy:
The other guy wants to swap because he thinks he'll gain.
So I refuse to swap, therefore I gain what he thought he would gain.

Unfortunately, your logic is far from impeccable.

Suppose you say to me: "Do you want to swap this used tampon for $1,000,000?"
I say "No."
Therefore I have just gained $1,000,000?

[roverthtaeh]

You under-rate used tampons

[Mbuna]

No you havnt gained 1Million you have NOT LOST 1million  BIG Difference

[roverthtaeh]

Yeah, and I've still got my tampon

[MrsLime]

You under-rate used tampons

Hey, I value used tampons as much as the next man, but I doubt you could present me with one so juicy and pungent that it was worth ONE MILLION DOLLARS.  Now you are just being silly.

[roverthtaeh]

You under-rate used tampons

Hey, I value used tampons as much as the next man, but I doubt you could present me with one so juicy and pungent that it was worth ONE MILLION DOLLARS.  Now you are just being silly.

What might one be worth from the private suite of, say... Angelina Jolie?
And could I try it on ebay?

[Claw75]

this thread has turned gross!

[byronkincaid]

Hey, I value used tampons as much as the next man

All my fantasies dashed... Oh well there's always that new character in Lost, Juliet