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View Full Version : Will somebody double check my math on this

TRBNGR
04-19-2005, 02:39 PM
Im looking to determine the probability that given a deck of X cards, Y of them the same (by rank[4] or suit[13]) what is the probability that at least one has been chosen after Z cards are dealt. To make it concrete lets use the discreet example of -- 'What is the probability that at least 1 heart has been chosen after 10 cards are dealt from a standard deck?'

Step 1)
1 - Probability of No hearts Dealt After 10 Cards

Step 2)
Probability of No hearts Dealt After 10 Cards =
Ways to choose 10 cards without a heart / Total Ways to Choose 10 cards

Step 3)
1 - [c(42, 10) / c(52,10)]

Is this correct?

and would the general formula be

1 - [c(X-Y,Z)/c(X,Z)]?

Cobra
04-19-2005, 02:48 PM
[ QUOTE ]
Step 1)
1 - Probability of No hearts Dealt After 10 Cards

[/ QUOTE ]

Correct

[ QUOTE ]
Probability of No hearts Dealt After 10 Cards =
Ways to choose 10 cards without a heart / Total Ways to Choose 10 cards

[/ QUOTE ]

Correct

[ QUOTE ]
1 - [c(42, 10) / c(52,10)]

[/ QUOTE ]

Incorrect. It needs to be 1-[c(39,10)/c(52,10)]
You have to choose the ten cards from the 39 that are not hearts.

Cobra

TRBNGR
04-19-2005, 03:01 PM
LoL! Thank you... Just like me to get the 'higher' level math correct and butcher the arthimetic.