Need help with a certain method of solving counting problems (designating a fixed element and then choosing the rest).
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How many decks of 13 cards are there that include at least one Jack, Queen, King or Ace?
I know you can subtract the amount of decks that don't include any of those, of which there are $binom3613$, from the total number of possible decks, $binom5213$, but I'd like to gain a better understanding of a different method:
can you solve it by designating a J/Q/K/A first (for which there are 16 choices) and then picking the other 12 cards? My initial thought was $16binom5112$ but then I count decks multiple times. Say I designate the King of Hearts and then pick 12 random cards, one of which happens to be an Ace of Clubs. Later I designate the Ace of Clubs and pick 12 random cards, one of which happens to be the King of Hearts. This deck is counted double now. But how do I eliminate all multiple countings? How do I calculate the exact amount of multiple countings?
Thanks in advance.
combinatorics
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How many decks of 13 cards are there that include at least one Jack, Queen, King or Ace?
I know you can subtract the amount of decks that don't include any of those, of which there are $binom3613$, from the total number of possible decks, $binom5213$, but I'd like to gain a better understanding of a different method:
can you solve it by designating a J/Q/K/A first (for which there are 16 choices) and then picking the other 12 cards? My initial thought was $16binom5112$ but then I count decks multiple times. Say I designate the King of Hearts and then pick 12 random cards, one of which happens to be an Ace of Clubs. Later I designate the Ace of Clubs and pick 12 random cards, one of which happens to be the King of Hearts. This deck is counted double now. But how do I eliminate all multiple countings? How do I calculate the exact amount of multiple countings?
Thanks in advance.
combinatorics
add a comment |Â
up vote
0
down vote
favorite
up vote
0
down vote
favorite
How many decks of 13 cards are there that include at least one Jack, Queen, King or Ace?
I know you can subtract the amount of decks that don't include any of those, of which there are $binom3613$, from the total number of possible decks, $binom5213$, but I'd like to gain a better understanding of a different method:
can you solve it by designating a J/Q/K/A first (for which there are 16 choices) and then picking the other 12 cards? My initial thought was $16binom5112$ but then I count decks multiple times. Say I designate the King of Hearts and then pick 12 random cards, one of which happens to be an Ace of Clubs. Later I designate the Ace of Clubs and pick 12 random cards, one of which happens to be the King of Hearts. This deck is counted double now. But how do I eliminate all multiple countings? How do I calculate the exact amount of multiple countings?
Thanks in advance.
combinatorics
How many decks of 13 cards are there that include at least one Jack, Queen, King or Ace?
I know you can subtract the amount of decks that don't include any of those, of which there are $binom3613$, from the total number of possible decks, $binom5213$, but I'd like to gain a better understanding of a different method:
can you solve it by designating a J/Q/K/A first (for which there are 16 choices) and then picking the other 12 cards? My initial thought was $16binom5112$ but then I count decks multiple times. Say I designate the King of Hearts and then pick 12 random cards, one of which happens to be an Ace of Clubs. Later I designate the Ace of Clubs and pick 12 random cards, one of which happens to be the King of Hearts. This deck is counted double now. But how do I eliminate all multiple countings? How do I calculate the exact amount of multiple countings?
Thanks in advance.
combinatorics
asked Aug 19 at 10:31
Surzilla
1087
1087
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Let $J$ denote the decks of $13$ cards out of $52$ that contain no Jack. Similar for $Q,K,A$.
Then with inclusion/exclusion and symmetry we find:$$|Jcup Qcup Kcup A|=4|J|-6|Jcap Q|+4|Jcap Qcap K|-|Jcap Qcap Kcap A|=$$$$4binom4813-6binom4413+4binom4013-binom3613$$
So that $$|J^complementcap Q^complementcap K^complementcap A^complement|=binom5213-4binom4813+6binom4413-4binom4013+binom3613$$
This is a nice solution but not really an answer to my question.
â Surzilla
Aug 19 at 10:58
1
Then do not accept it. But answering your question(s) point by point is quite cumbersome. Also the inclusion/exclusion method is exactly a way to eliminate double countings whatsoever.
â drhab
Aug 19 at 11:05
add a comment |Â
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
2
down vote
Let $J$ denote the decks of $13$ cards out of $52$ that contain no Jack. Similar for $Q,K,A$.
Then with inclusion/exclusion and symmetry we find:$$|Jcup Qcup Kcup A|=4|J|-6|Jcap Q|+4|Jcap Qcap K|-|Jcap Qcap Kcap A|=$$$$4binom4813-6binom4413+4binom4013-binom3613$$
So that $$|J^complementcap Q^complementcap K^complementcap A^complement|=binom5213-4binom4813+6binom4413-4binom4013+binom3613$$
This is a nice solution but not really an answer to my question.
â Surzilla
Aug 19 at 10:58
1
Then do not accept it. But answering your question(s) point by point is quite cumbersome. Also the inclusion/exclusion method is exactly a way to eliminate double countings whatsoever.
â drhab
Aug 19 at 11:05
add a comment |Â
up vote
2
down vote
Let $J$ denote the decks of $13$ cards out of $52$ that contain no Jack. Similar for $Q,K,A$.
Then with inclusion/exclusion and symmetry we find:$$|Jcup Qcup Kcup A|=4|J|-6|Jcap Q|+4|Jcap Qcap K|-|Jcap Qcap Kcap A|=$$$$4binom4813-6binom4413+4binom4013-binom3613$$
So that $$|J^complementcap Q^complementcap K^complementcap A^complement|=binom5213-4binom4813+6binom4413-4binom4013+binom3613$$
This is a nice solution but not really an answer to my question.
â Surzilla
Aug 19 at 10:58
1
Then do not accept it. But answering your question(s) point by point is quite cumbersome. Also the inclusion/exclusion method is exactly a way to eliminate double countings whatsoever.
â drhab
Aug 19 at 11:05
add a comment |Â
up vote
2
down vote
up vote
2
down vote
Let $J$ denote the decks of $13$ cards out of $52$ that contain no Jack. Similar for $Q,K,A$.
Then with inclusion/exclusion and symmetry we find:$$|Jcup Qcup Kcup A|=4|J|-6|Jcap Q|+4|Jcap Qcap K|-|Jcap Qcap Kcap A|=$$$$4binom4813-6binom4413+4binom4013-binom3613$$
So that $$|J^complementcap Q^complementcap K^complementcap A^complement|=binom5213-4binom4813+6binom4413-4binom4013+binom3613$$
Let $J$ denote the decks of $13$ cards out of $52$ that contain no Jack. Similar for $Q,K,A$.
Then with inclusion/exclusion and symmetry we find:$$|Jcup Qcup Kcup A|=4|J|-6|Jcap Q|+4|Jcap Qcap K|-|Jcap Qcap Kcap A|=$$$$4binom4813-6binom4413+4binom4013-binom3613$$
So that $$|J^complementcap Q^complementcap K^complementcap A^complement|=binom5213-4binom4813+6binom4413-4binom4013+binom3613$$
answered Aug 19 at 10:49
drhab
87.7k541119
87.7k541119
This is a nice solution but not really an answer to my question.
â Surzilla
Aug 19 at 10:58
1
Then do not accept it. But answering your question(s) point by point is quite cumbersome. Also the inclusion/exclusion method is exactly a way to eliminate double countings whatsoever.
â drhab
Aug 19 at 11:05
add a comment |Â
This is a nice solution but not really an answer to my question.
â Surzilla
Aug 19 at 10:58
1
Then do not accept it. But answering your question(s) point by point is quite cumbersome. Also the inclusion/exclusion method is exactly a way to eliminate double countings whatsoever.
â drhab
Aug 19 at 11:05
This is a nice solution but not really an answer to my question.
â Surzilla
Aug 19 at 10:58
This is a nice solution but not really an answer to my question.
â Surzilla
Aug 19 at 10:58
1
1
Then do not accept it. But answering your question(s) point by point is quite cumbersome. Also the inclusion/exclusion method is exactly a way to eliminate double countings whatsoever.
â drhab
Aug 19 at 11:05
Then do not accept it. But answering your question(s) point by point is quite cumbersome. Also the inclusion/exclusion method is exactly a way to eliminate double countings whatsoever.
â drhab
Aug 19 at 11:05
add a comment |Â
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