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'''[[MA 375 Spring 09 HW 5|Back]]'''
 
'''[[MA 375 Spring 09 HW 5|Back]]'''
  
I am confused with what numbers I should put on top of my probability fraction.  I have three numbers: # of ways for someone to choose 7 #s from 80 = C(80,7), # of ways for the computer to choose 11 numbers from 80 = C(80,11), and # of ways someone could have chosen the 7 from the 11 = C(11, 7).  I think I understand that the number C(11, 7) is the total number of lottery numbers that are winners.  And that the total number of lottery number is C(80, 11), but what do I do with C(80,7)?
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By a hand containing 5 different kinds, is this including face value, suit and sequence or just face value?
  
~James Gilmore
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I think it's just face value, because 5 different suits wouldn't make sense. -Zoe
  
I'm not sure if this is right, but my answer was C(11,7)/C(80,7). -Zoe
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13 different kinds and 4 different suits
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i did (13 choose 5)*4 on top (to represent there are 13 numbers, pick one ad then taking the suits into account - ace of hearts is different from ace of spades) and (52 choose 5) on the bottom to show all the possible hands with 5 cards.
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I think that is mostly right but I believe it should be (13 choose 5)*4^5, in order to account for there being 4 choices for each of the kinds.--[[User:Spfeifer|Spfeifer]] 16:55, 18 February 2009 (UTC)
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I haven't confirmed this solution with anyone, but I found it easier to get the probability of the complement, having a hand with at least two cards of the same type. For the top: Choose any card (52C1), choose another card of that type (3C1) and choose 3 arbitrary cards (50C3)-[[User:jdrummon|jdrummon]]
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Finding the complement, I think, would take a lot longer because you not only have to find the probability of getting a hand with 2 cards the same but getting a hand with 3 cards, 4 cards, and 5 cards the same and them sum these probabilities. Also, using the method you gave above will lead to over count. -[[User:cwithey|cwithey]]

Latest revision as of 09:48, 19 February 2009

Back

By a hand containing 5 different kinds, is this including face value, suit and sequence or just face value?

I think it's just face value, because 5 different suits wouldn't make sense. -Zoe

13 different kinds and 4 different suits

i did (13 choose 5)*4 on top (to represent there are 13 numbers, pick one ad then taking the suits into account - ace of hearts is different from ace of spades) and (52 choose 5) on the bottom to show all the possible hands with 5 cards.

I think that is mostly right but I believe it should be (13 choose 5)*4^5, in order to account for there being 4 choices for each of the kinds.--Spfeifer 16:55, 18 February 2009 (UTC)

I haven't confirmed this solution with anyone, but I found it easier to get the probability of the complement, having a hand with at least two cards of the same type. For the top: Choose any card (52C1), choose another card of that type (3C1) and choose 3 arbitrary cards (50C3)-jdrummon

Finding the complement, I think, would take a lot longer because you not only have to find the probability of getting a hand with 2 cards the same but getting a hand with 3 cards, 4 cards, and 5 cards the same and them sum these probabilities. Also, using the method you gave above will lead to over count. -cwithey

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