How do I myself compute the following probability

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I tried to approximate binomial to a poisson distribution but this did not match the conditions since n is too small.
Afterwards I considered the event Y equal the square root of X as being an intersection of 2 independents events Which means this is equal to the probability of y times the probability of square root of x.
however, here the square root really confuses me and in general I have thought about it too much but I am stuck.







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  • Before posting another question it would be nice checking the answers/giving a reply to the answers of your previous questions.
    – callculus
    Jul 14 at 16:10











  • I am so sorry if I did not reply to the previous questions, but I can tell you that I checked all of the explanations. i can just say that this site is perfect. The people answering are experts and have deep knowledge of probability. I am really stunned. I’ve been stuck for many day on those questions and they help me solve it in just few minutes
    – Roy Rizk
    Jul 14 at 16:15











  • You can mark the questions as answered by clicking on the checkmark at your favorable answer. The advantage for all users is, that everybody can see which questions are answered and which questions are not answered.
    – callculus
    Jul 14 at 16:20










  • In R: i = c(0,1,4); sum(dbinom(i,7,1/4)*dpois(sqrt(i), 3)) returns 0.0660885. Same as @BrianTung's Answer (+1). Also less elegantly, an approximation by simulation mean(replicate(10^6, rbinom(1, 7, 1/4)==(rpois(1,3))^2)) returns 0.066067, correct to three places.
    – BruceET
    Jul 14 at 16:38















up vote
0
down vote

favorite












enter image description here
I tried to approximate binomial to a poisson distribution but this did not match the conditions since n is too small.
Afterwards I considered the event Y equal the square root of X as being an intersection of 2 independents events Which means this is equal to the probability of y times the probability of square root of x.
however, here the square root really confuses me and in general I have thought about it too much but I am stuck.







share|cite|improve this question





















  • Before posting another question it would be nice checking the answers/giving a reply to the answers of your previous questions.
    – callculus
    Jul 14 at 16:10











  • I am so sorry if I did not reply to the previous questions, but I can tell you that I checked all of the explanations. i can just say that this site is perfect. The people answering are experts and have deep knowledge of probability. I am really stunned. I’ve been stuck for many day on those questions and they help me solve it in just few minutes
    – Roy Rizk
    Jul 14 at 16:15











  • You can mark the questions as answered by clicking on the checkmark at your favorable answer. The advantage for all users is, that everybody can see which questions are answered and which questions are not answered.
    – callculus
    Jul 14 at 16:20










  • In R: i = c(0,1,4); sum(dbinom(i,7,1/4)*dpois(sqrt(i), 3)) returns 0.0660885. Same as @BrianTung's Answer (+1). Also less elegantly, an approximation by simulation mean(replicate(10^6, rbinom(1, 7, 1/4)==(rpois(1,3))^2)) returns 0.066067, correct to three places.
    – BruceET
    Jul 14 at 16:38













up vote
0
down vote

favorite









up vote
0
down vote

favorite











enter image description here
I tried to approximate binomial to a poisson distribution but this did not match the conditions since n is too small.
Afterwards I considered the event Y equal the square root of X as being an intersection of 2 independents events Which means this is equal to the probability of y times the probability of square root of x.
however, here the square root really confuses me and in general I have thought about it too much but I am stuck.







share|cite|improve this question













enter image description here
I tried to approximate binomial to a poisson distribution but this did not match the conditions since n is too small.
Afterwards I considered the event Y equal the square root of X as being an intersection of 2 independents events Which means this is equal to the probability of y times the probability of square root of x.
however, here the square root really confuses me and in general I have thought about it too much but I am stuck.









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edited Jul 14 at 16:19









Alex Francisco

15.7k92047




15.7k92047









asked Jul 14 at 16:08









Roy Rizk

887




887











  • Before posting another question it would be nice checking the answers/giving a reply to the answers of your previous questions.
    – callculus
    Jul 14 at 16:10











  • I am so sorry if I did not reply to the previous questions, but I can tell you that I checked all of the explanations. i can just say that this site is perfect. The people answering are experts and have deep knowledge of probability. I am really stunned. I’ve been stuck for many day on those questions and they help me solve it in just few minutes
    – Roy Rizk
    Jul 14 at 16:15











  • You can mark the questions as answered by clicking on the checkmark at your favorable answer. The advantage for all users is, that everybody can see which questions are answered and which questions are not answered.
    – callculus
    Jul 14 at 16:20










  • In R: i = c(0,1,4); sum(dbinom(i,7,1/4)*dpois(sqrt(i), 3)) returns 0.0660885. Same as @BrianTung's Answer (+1). Also less elegantly, an approximation by simulation mean(replicate(10^6, rbinom(1, 7, 1/4)==(rpois(1,3))^2)) returns 0.066067, correct to three places.
    – BruceET
    Jul 14 at 16:38

















  • Before posting another question it would be nice checking the answers/giving a reply to the answers of your previous questions.
    – callculus
    Jul 14 at 16:10











  • I am so sorry if I did not reply to the previous questions, but I can tell you that I checked all of the explanations. i can just say that this site is perfect. The people answering are experts and have deep knowledge of probability. I am really stunned. I’ve been stuck for many day on those questions and they help me solve it in just few minutes
    – Roy Rizk
    Jul 14 at 16:15











  • You can mark the questions as answered by clicking on the checkmark at your favorable answer. The advantage for all users is, that everybody can see which questions are answered and which questions are not answered.
    – callculus
    Jul 14 at 16:20










  • In R: i = c(0,1,4); sum(dbinom(i,7,1/4)*dpois(sqrt(i), 3)) returns 0.0660885. Same as @BrianTung's Answer (+1). Also less elegantly, an approximation by simulation mean(replicate(10^6, rbinom(1, 7, 1/4)==(rpois(1,3))^2)) returns 0.066067, correct to three places.
    – BruceET
    Jul 14 at 16:38
















Before posting another question it would be nice checking the answers/giving a reply to the answers of your previous questions.
– callculus
Jul 14 at 16:10





Before posting another question it would be nice checking the answers/giving a reply to the answers of your previous questions.
– callculus
Jul 14 at 16:10













I am so sorry if I did not reply to the previous questions, but I can tell you that I checked all of the explanations. i can just say that this site is perfect. The people answering are experts and have deep knowledge of probability. I am really stunned. I’ve been stuck for many day on those questions and they help me solve it in just few minutes
– Roy Rizk
Jul 14 at 16:15





I am so sorry if I did not reply to the previous questions, but I can tell you that I checked all of the explanations. i can just say that this site is perfect. The people answering are experts and have deep knowledge of probability. I am really stunned. I’ve been stuck for many day on those questions and they help me solve it in just few minutes
– Roy Rizk
Jul 14 at 16:15













You can mark the questions as answered by clicking on the checkmark at your favorable answer. The advantage for all users is, that everybody can see which questions are answered and which questions are not answered.
– callculus
Jul 14 at 16:20




You can mark the questions as answered by clicking on the checkmark at your favorable answer. The advantage for all users is, that everybody can see which questions are answered and which questions are not answered.
– callculus
Jul 14 at 16:20












In R: i = c(0,1,4); sum(dbinom(i,7,1/4)*dpois(sqrt(i), 3)) returns 0.0660885. Same as @BrianTung's Answer (+1). Also less elegantly, an approximation by simulation mean(replicate(10^6, rbinom(1, 7, 1/4)==(rpois(1,3))^2)) returns 0.066067, correct to three places.
– BruceET
Jul 14 at 16:38





In R: i = c(0,1,4); sum(dbinom(i,7,1/4)*dpois(sqrt(i), 3)) returns 0.0660885. Same as @BrianTung's Answer (+1). Also less elegantly, an approximation by simulation mean(replicate(10^6, rbinom(1, 7, 1/4)==(rpois(1,3))^2)) returns 0.066067, correct to three places.
– BruceET
Jul 14 at 16:38











2 Answers
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begineqnarray* P(sqrtX=Y) &=& sum _k=0^2 P(sqrtX=kcap Y=k)\
&=& sum _k=0^2 P(sqrtX=k)P(Y=k)\
&=& sum _k=0^2 P(X=k^2)P(Y=k)\
endeqnarray*






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    Note that $X$ is constrained to be an integer between $0$ and $7$, and $Y$ is constrained to be an integer. That means that for $sqrtX = Y$ to hold, $X$ must be $0$, $1$, or $4$. I would compute these probabilities explicitly and just calculate



    $$
    P(X = 0)P(Y = 0) + P(X = 1)P(Y = 1) + P(X = 4)P(Y = 2)
    $$






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      2 Answers
      2






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      2 Answers
      2






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      active

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      up vote
      1
      down vote



      accepted










      begineqnarray* P(sqrtX=Y) &=& sum _k=0^2 P(sqrtX=kcap Y=k)\
      &=& sum _k=0^2 P(sqrtX=k)P(Y=k)\
      &=& sum _k=0^2 P(X=k^2)P(Y=k)\
      endeqnarray*






      share|cite|improve this answer

























        up vote
        1
        down vote



        accepted










        begineqnarray* P(sqrtX=Y) &=& sum _k=0^2 P(sqrtX=kcap Y=k)\
        &=& sum _k=0^2 P(sqrtX=k)P(Y=k)\
        &=& sum _k=0^2 P(X=k^2)P(Y=k)\
        endeqnarray*






        share|cite|improve this answer























          up vote
          1
          down vote



          accepted







          up vote
          1
          down vote



          accepted






          begineqnarray* P(sqrtX=Y) &=& sum _k=0^2 P(sqrtX=kcap Y=k)\
          &=& sum _k=0^2 P(sqrtX=k)P(Y=k)\
          &=& sum _k=0^2 P(X=k^2)P(Y=k)\
          endeqnarray*






          share|cite|improve this answer













          begineqnarray* P(sqrtX=Y) &=& sum _k=0^2 P(sqrtX=kcap Y=k)\
          &=& sum _k=0^2 P(sqrtX=k)P(Y=k)\
          &=& sum _k=0^2 P(X=k^2)P(Y=k)\
          endeqnarray*







          share|cite|improve this answer













          share|cite|improve this answer



          share|cite|improve this answer











          answered Jul 14 at 16:27









          greedoid

          26.6k93574




          26.6k93574




















              up vote
              3
              down vote













              Note that $X$ is constrained to be an integer between $0$ and $7$, and $Y$ is constrained to be an integer. That means that for $sqrtX = Y$ to hold, $X$ must be $0$, $1$, or $4$. I would compute these probabilities explicitly and just calculate



              $$
              P(X = 0)P(Y = 0) + P(X = 1)P(Y = 1) + P(X = 4)P(Y = 2)
              $$






              share|cite|improve this answer

























                up vote
                3
                down vote













                Note that $X$ is constrained to be an integer between $0$ and $7$, and $Y$ is constrained to be an integer. That means that for $sqrtX = Y$ to hold, $X$ must be $0$, $1$, or $4$. I would compute these probabilities explicitly and just calculate



                $$
                P(X = 0)P(Y = 0) + P(X = 1)P(Y = 1) + P(X = 4)P(Y = 2)
                $$






                share|cite|improve this answer























                  up vote
                  3
                  down vote










                  up vote
                  3
                  down vote









                  Note that $X$ is constrained to be an integer between $0$ and $7$, and $Y$ is constrained to be an integer. That means that for $sqrtX = Y$ to hold, $X$ must be $0$, $1$, or $4$. I would compute these probabilities explicitly and just calculate



                  $$
                  P(X = 0)P(Y = 0) + P(X = 1)P(Y = 1) + P(X = 4)P(Y = 2)
                  $$






                  share|cite|improve this answer













                  Note that $X$ is constrained to be an integer between $0$ and $7$, and $Y$ is constrained to be an integer. That means that for $sqrtX = Y$ to hold, $X$ must be $0$, $1$, or $4$. I would compute these probabilities explicitly and just calculate



                  $$
                  P(X = 0)P(Y = 0) + P(X = 1)P(Y = 1) + P(X = 4)P(Y = 2)
                  $$







                  share|cite|improve this answer













                  share|cite|improve this answer



                  share|cite|improve this answer











                  answered Jul 14 at 16:25









                  Brian Tung

                  25.3k32453




                  25.3k32453






















                       

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