find the probability that two experiments matches in at least one number












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Suppose you have an urn with $N$ different balls numbered from $1$ to $N$. One experiment consist in sustracting $k$ balls without reposition.



Find the probability that if you perform 2 experiments there will be at least one number appearing in both experiments, for example: in $1,3,5,7,9$ and $1,2,10,11,12$ both experiments contain the number $1$.



I'm not sure if the answer has a simple form because I asked this to myself. I was playing a game and I needed the answer for the case $N=74$ and $k=5$ ( I don't know the answer for this case yet either).



The total number of possible experiments is $binom{N}{k}$, therefore if I perform $2$ experiments the total cases is given by $binom{N}{k}^2$. I don't know how to compute the favorable cases.
My idea is to start with an specific experiment (let's say $1,2,3,4,5$) and compute the number of experiments that contain any of this numbers.










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$endgroup$

















    0












    $begingroup$


    Suppose you have an urn with $N$ different balls numbered from $1$ to $N$. One experiment consist in sustracting $k$ balls without reposition.



    Find the probability that if you perform 2 experiments there will be at least one number appearing in both experiments, for example: in $1,3,5,7,9$ and $1,2,10,11,12$ both experiments contain the number $1$.



    I'm not sure if the answer has a simple form because I asked this to myself. I was playing a game and I needed the answer for the case $N=74$ and $k=5$ ( I don't know the answer for this case yet either).



    The total number of possible experiments is $binom{N}{k}$, therefore if I perform $2$ experiments the total cases is given by $binom{N}{k}^2$. I don't know how to compute the favorable cases.
    My idea is to start with an specific experiment (let's say $1,2,3,4,5$) and compute the number of experiments that contain any of this numbers.










    share|cite|improve this question









    $endgroup$















      0












      0








      0





      $begingroup$


      Suppose you have an urn with $N$ different balls numbered from $1$ to $N$. One experiment consist in sustracting $k$ balls without reposition.



      Find the probability that if you perform 2 experiments there will be at least one number appearing in both experiments, for example: in $1,3,5,7,9$ and $1,2,10,11,12$ both experiments contain the number $1$.



      I'm not sure if the answer has a simple form because I asked this to myself. I was playing a game and I needed the answer for the case $N=74$ and $k=5$ ( I don't know the answer for this case yet either).



      The total number of possible experiments is $binom{N}{k}$, therefore if I perform $2$ experiments the total cases is given by $binom{N}{k}^2$. I don't know how to compute the favorable cases.
      My idea is to start with an specific experiment (let's say $1,2,3,4,5$) and compute the number of experiments that contain any of this numbers.










      share|cite|improve this question









      $endgroup$




      Suppose you have an urn with $N$ different balls numbered from $1$ to $N$. One experiment consist in sustracting $k$ balls without reposition.



      Find the probability that if you perform 2 experiments there will be at least one number appearing in both experiments, for example: in $1,3,5,7,9$ and $1,2,10,11,12$ both experiments contain the number $1$.



      I'm not sure if the answer has a simple form because I asked this to myself. I was playing a game and I needed the answer for the case $N=74$ and $k=5$ ( I don't know the answer for this case yet either).



      The total number of possible experiments is $binom{N}{k}$, therefore if I perform $2$ experiments the total cases is given by $binom{N}{k}^2$. I don't know how to compute the favorable cases.
      My idea is to start with an specific experiment (let's say $1,2,3,4,5$) and compute the number of experiments that contain any of this numbers.







      probability combinatorics






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      asked Jan 23 at 16:19









      CarvalCarval

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          $begingroup$

          You can just imagine that you draw the balls $1$ to $k$ in the first draw. Otherwise you can renumber the balls. Now ask the chance you don't get a number from $1$ to $k$ in the second draw and subtract from $1$. You get
          $$1-frac {N-k choose k}{N choose k}$$






          share|cite|improve this answer









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            $begingroup$

            You can just imagine that you draw the balls $1$ to $k$ in the first draw. Otherwise you can renumber the balls. Now ask the chance you don't get a number from $1$ to $k$ in the second draw and subtract from $1$. You get
            $$1-frac {N-k choose k}{N choose k}$$






            share|cite|improve this answer









            $endgroup$


















              0












              $begingroup$

              You can just imagine that you draw the balls $1$ to $k$ in the first draw. Otherwise you can renumber the balls. Now ask the chance you don't get a number from $1$ to $k$ in the second draw and subtract from $1$. You get
              $$1-frac {N-k choose k}{N choose k}$$






              share|cite|improve this answer









              $endgroup$
















                0












                0








                0





                $begingroup$

                You can just imagine that you draw the balls $1$ to $k$ in the first draw. Otherwise you can renumber the balls. Now ask the chance you don't get a number from $1$ to $k$ in the second draw and subtract from $1$. You get
                $$1-frac {N-k choose k}{N choose k}$$






                share|cite|improve this answer









                $endgroup$



                You can just imagine that you draw the balls $1$ to $k$ in the first draw. Otherwise you can renumber the balls. Now ask the chance you don't get a number from $1$ to $k$ in the second draw and subtract from $1$. You get
                $$1-frac {N-k choose k}{N choose k}$$







                share|cite|improve this answer












                share|cite|improve this answer



                share|cite|improve this answer










                answered Jan 23 at 16:22









                Ross MillikanRoss Millikan

                299k24200374




                299k24200374






























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