Let $Xsim Poi(10) $ and $Y sim exp(frac{1}{10})$ independent. Why $P(X+Yleqfrac{3}{2}) = P(X=0, Y leq...












1












$begingroup$


Let $Xsim Poi(10) $ and $Y sim exp(frac{1}{10})$ independent random raviables



I would like to compute:
$P(X+Yleqfrac{3}{2})$



So what I did, which is probably wrong, is the following:



Let $X=k$ then $P(X+Yleqfrac{3}{2})=P(X=k, Yleqfrac{3}{2}-k)$



But I don't know how to take it from there.



The solution on the other hand computes it as follows:



$P(X+Yleqfrac{3}{2}) = P(X=0, Y leq frac{3}{2}) + P(X=1,Yleq frac {1}{2})$



But why does $Xin${0,1} ? it doesn't make much sense to me.



Thanks!!










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    1












    $begingroup$


    Let $Xsim Poi(10) $ and $Y sim exp(frac{1}{10})$ independent random raviables



    I would like to compute:
    $P(X+Yleqfrac{3}{2})$



    So what I did, which is probably wrong, is the following:



    Let $X=k$ then $P(X+Yleqfrac{3}{2})=P(X=k, Yleqfrac{3}{2}-k)$



    But I don't know how to take it from there.



    The solution on the other hand computes it as follows:



    $P(X+Yleqfrac{3}{2}) = P(X=0, Y leq frac{3}{2}) + P(X=1,Yleq frac {1}{2})$



    But why does $Xin${0,1} ? it doesn't make much sense to me.



    Thanks!!










    share|cite|improve this question









    $endgroup$















      1












      1








      1





      $begingroup$


      Let $Xsim Poi(10) $ and $Y sim exp(frac{1}{10})$ independent random raviables



      I would like to compute:
      $P(X+Yleqfrac{3}{2})$



      So what I did, which is probably wrong, is the following:



      Let $X=k$ then $P(X+Yleqfrac{3}{2})=P(X=k, Yleqfrac{3}{2}-k)$



      But I don't know how to take it from there.



      The solution on the other hand computes it as follows:



      $P(X+Yleqfrac{3}{2}) = P(X=0, Y leq frac{3}{2}) + P(X=1,Yleq frac {1}{2})$



      But why does $Xin${0,1} ? it doesn't make much sense to me.



      Thanks!!










      share|cite|improve this question









      $endgroup$




      Let $Xsim Poi(10) $ and $Y sim exp(frac{1}{10})$ independent random raviables



      I would like to compute:
      $P(X+Yleqfrac{3}{2})$



      So what I did, which is probably wrong, is the following:



      Let $X=k$ then $P(X+Yleqfrac{3}{2})=P(X=k, Yleqfrac{3}{2}-k)$



      But I don't know how to take it from there.



      The solution on the other hand computes it as follows:



      $P(X+Yleqfrac{3}{2}) = P(X=0, Y leq frac{3}{2}) + P(X=1,Yleq frac {1}{2})$



      But why does $Xin${0,1} ? it doesn't make much sense to me.



      Thanks!!







      probability poisson-distribution exponential-distribution






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      asked Jan 30 at 9:50









      superuser123superuser123

      48628




      48628






















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          $begingroup$

          $X$ and $Y$ take only non-negative integer values. $X+Y leq frac 3 2$ implies $Xleq frac 3 2$ and the only integers less than or equal to $frac 3 2$ are $0$ and $1$.






          share|cite|improve this answer









          $endgroup$





















            1












            $begingroup$

            That's because $X in mathbb{N} cup {0}$ and $Y > 0$, so $X + Y$ can only be below $3/2$ when $X = 0$ or $X = 1$.






            share|cite|improve this answer









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              $begingroup$

              $X$ and $Y$ take only non-negative integer values. $X+Y leq frac 3 2$ implies $Xleq frac 3 2$ and the only integers less than or equal to $frac 3 2$ are $0$ and $1$.






              share|cite|improve this answer









              $endgroup$


















                1












                $begingroup$

                $X$ and $Y$ take only non-negative integer values. $X+Y leq frac 3 2$ implies $Xleq frac 3 2$ and the only integers less than or equal to $frac 3 2$ are $0$ and $1$.






                share|cite|improve this answer









                $endgroup$
















                  1












                  1








                  1





                  $begingroup$

                  $X$ and $Y$ take only non-negative integer values. $X+Y leq frac 3 2$ implies $Xleq frac 3 2$ and the only integers less than or equal to $frac 3 2$ are $0$ and $1$.






                  share|cite|improve this answer









                  $endgroup$



                  $X$ and $Y$ take only non-negative integer values. $X+Y leq frac 3 2$ implies $Xleq frac 3 2$ and the only integers less than or equal to $frac 3 2$ are $0$ and $1$.







                  share|cite|improve this answer












                  share|cite|improve this answer



                  share|cite|improve this answer










                  answered Jan 30 at 9:56









                  Kavi Rama MurthyKavi Rama Murthy

                  71.9k53170




                  71.9k53170























                      1












                      $begingroup$

                      That's because $X in mathbb{N} cup {0}$ and $Y > 0$, so $X + Y$ can only be below $3/2$ when $X = 0$ or $X = 1$.






                      share|cite|improve this answer









                      $endgroup$


















                        1












                        $begingroup$

                        That's because $X in mathbb{N} cup {0}$ and $Y > 0$, so $X + Y$ can only be below $3/2$ when $X = 0$ or $X = 1$.






                        share|cite|improve this answer









                        $endgroup$
















                          1












                          1








                          1





                          $begingroup$

                          That's because $X in mathbb{N} cup {0}$ and $Y > 0$, so $X + Y$ can only be below $3/2$ when $X = 0$ or $X = 1$.






                          share|cite|improve this answer









                          $endgroup$



                          That's because $X in mathbb{N} cup {0}$ and $Y > 0$, so $X + Y$ can only be below $3/2$ when $X = 0$ or $X = 1$.







                          share|cite|improve this answer












                          share|cite|improve this answer



                          share|cite|improve this answer










                          answered Jan 30 at 9:57









                          HarnakHarnak

                          1,334512




                          1,334512






























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