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don't you hate it when you hear a question on a quiz show and you know that the answer they say is right is the wrong one.

"If you toss two coins, what's the probability that both show the same face ?"

They said 1 in 4, but unless they've changed the laws of probability since i was at school it's 1 in 2.

keep to the Fen Causeway

by Helen (lareinagal at yahoo dot co dot uk) on Tue Jan 13th, 2009 at 01:15:22 PM EST
Let's see:

Case 1: Both show same
Case 2: Mis-match -- one heads, one tails
Case 3: One disappears in a burst of existential uncertainty
Case 4: Both disappear in a burst of existential uncertainty

So ... yeah ... 1/4.

:-)

(For my next magical trick I prove how reducing the temperature of an object to negative degrees Kelvin creates a container of negative volume into which you can stuff an infinite amount of stuff.)

((There.  That outta explode Mig's head.))

by ATinNM on Tue Jan 13th, 2009 at 01:28:06 PM EST
[ Parent ]
Shorter Helen: "Math is for Communists."

Conservatives want live babies so they can raise them to be dead soldiers. - George Carlin
by Drew J Jones (myfriends@thisispancakes.com) on Tue Jan 13th, 2009 at 01:30:01 PM EST
[ Parent ]
It's a trick question, because anyone who actually still had any money surely would have stashed it in the Cayman Islands by now and not wasted time on coin tossing when Karl Marx is about to be sworn in as president.

"The basis of optimism is sheer terror" - Oscar Wilde
by NordicStorm (michael<-at->sturmbaum.net) on Tue Jan 13th, 2009 at 02:32:09 PM EST
[ Parent ]
Unanswerable, without knowledge wether the coins are identical, and if not odds that two random coins will have the same persons head on the side.

Any idiot can face a crisis - it's day to day living that wears you out.
by ceebs (ceebs (at) eurotrib (dot) com) on Tue Jan 13th, 2009 at 01:43:58 PM EST
[ Parent ]
pedant

keep to the Fen Causeway
by Helen (lareinagal at yahoo dot co dot uk) on Tue Jan 13th, 2009 at 01:45:17 PM EST
[ Parent ]
Maybe they mean "two heads"?

Most economists teach a theoretical framework that has been shown to be fundamentally useless. -- James K. Galbraith
by Migeru (migeru at eurotrib dot com) on Tue Jan 13th, 2009 at 01:55:46 PM EST
[ Parent ]
thats what I wondered, but either the question was wrong or the answer was wrong.

keep to the Fen Causeway
by Helen (lareinagal at yahoo dot co dot uk) on Tue Jan 13th, 2009 at 02:14:04 PM EST
[ Parent ]
Are they tossed starting with both having the same side facing up? As shown in this paper, the probability of a coin ending up with the same side facing up as you started with is about .51, leading to a probability of about .5002 for your problem. (If the first author of this paper is the one flipping the coin, the probability is apparently whatever he wants it to be - his first career was as a professional magician...)
by gk (g k quattro due due sette "at" gmail.com) on Tue Jan 13th, 2009 at 02:29:05 PM EST
[ Parent ]

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