using Central Limit Theorem to approximate a probability with large 'n'












1












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For $i>1$ , let $X_i$ ~ $G_{1/2}$ be distributed Geometrically with parameter $1/2$.



$$ Y_n= frac{1}{sqrt n} sum_{r=1}^n X_r-2 $$



Approximate $P(-1le Y_nle 2)$ with large n.($Y_n$ is not properly normalized)



My attempt-

normalised $Y_n = frac{1}{sqrt n} sum_{r=1}^n frac{(X_r-2)-E[X_r-2]}{V[X-2]*n}$



then approximating $P(-1le Y_nle 2)$ I got the answer as 0.4332 which is incorrect. Can anybody give me the correct solution of this question.










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  • $begingroup$
    @Damandeep Its an online course in probability and stats
    $endgroup$
    – Kriti Arora
    Dec 14 '18 at 11:43
















1












$begingroup$


For $i>1$ , let $X_i$ ~ $G_{1/2}$ be distributed Geometrically with parameter $1/2$.



$$ Y_n= frac{1}{sqrt n} sum_{r=1}^n X_r-2 $$



Approximate $P(-1le Y_nle 2)$ with large n.($Y_n$ is not properly normalized)



My attempt-

normalised $Y_n = frac{1}{sqrt n} sum_{r=1}^n frac{(X_r-2)-E[X_r-2]}{V[X-2]*n}$



then approximating $P(-1le Y_nle 2)$ I got the answer as 0.4332 which is incorrect. Can anybody give me the correct solution of this question.










share|cite|improve this question









$endgroup$












  • $begingroup$
    @Damandeep Its an online course in probability and stats
    $endgroup$
    – Kriti Arora
    Dec 14 '18 at 11:43














1












1








1





$begingroup$


For $i>1$ , let $X_i$ ~ $G_{1/2}$ be distributed Geometrically with parameter $1/2$.



$$ Y_n= frac{1}{sqrt n} sum_{r=1}^n X_r-2 $$



Approximate $P(-1le Y_nle 2)$ with large n.($Y_n$ is not properly normalized)



My attempt-

normalised $Y_n = frac{1}{sqrt n} sum_{r=1}^n frac{(X_r-2)-E[X_r-2]}{V[X-2]*n}$



then approximating $P(-1le Y_nle 2)$ I got the answer as 0.4332 which is incorrect. Can anybody give me the correct solution of this question.










share|cite|improve this question









$endgroup$




For $i>1$ , let $X_i$ ~ $G_{1/2}$ be distributed Geometrically with parameter $1/2$.



$$ Y_n= frac{1}{sqrt n} sum_{r=1}^n X_r-2 $$



Approximate $P(-1le Y_nle 2)$ with large n.($Y_n$ is not properly normalized)



My attempt-

normalised $Y_n = frac{1}{sqrt n} sum_{r=1}^n frac{(X_r-2)-E[X_r-2]}{V[X-2]*n}$



then approximating $P(-1le Y_nle 2)$ I got the answer as 0.4332 which is incorrect. Can anybody give me the correct solution of this question.







statistics central-limit-theorem






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asked Dec 8 '18 at 10:15









Kriti AroraKriti Arora

396




396












  • $begingroup$
    @Damandeep Its an online course in probability and stats
    $endgroup$
    – Kriti Arora
    Dec 14 '18 at 11:43


















  • $begingroup$
    @Damandeep Its an online course in probability and stats
    $endgroup$
    – Kriti Arora
    Dec 14 '18 at 11:43
















$begingroup$
@Damandeep Its an online course in probability and stats
$endgroup$
– Kriti Arora
Dec 14 '18 at 11:43




$begingroup$
@Damandeep Its an online course in probability and stats
$endgroup$
– Kriti Arora
Dec 14 '18 at 11:43










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Like $X_r-2$, $Y_n$ has mean $0$ and variance $2$. The answer is therefore $Phi(sqrt{2})-Phi(frac{-1}{sqrt{2}})approx 0.6816$.






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    1












    $begingroup$

    Like $X_r-2$, $Y_n$ has mean $0$ and variance $2$. The answer is therefore $Phi(sqrt{2})-Phi(frac{-1}{sqrt{2}})approx 0.6816$.






    share|cite|improve this answer









    $endgroup$


















      1












      $begingroup$

      Like $X_r-2$, $Y_n$ has mean $0$ and variance $2$. The answer is therefore $Phi(sqrt{2})-Phi(frac{-1}{sqrt{2}})approx 0.6816$.






      share|cite|improve this answer









      $endgroup$
















        1












        1








        1





        $begingroup$

        Like $X_r-2$, $Y_n$ has mean $0$ and variance $2$. The answer is therefore $Phi(sqrt{2})-Phi(frac{-1}{sqrt{2}})approx 0.6816$.






        share|cite|improve this answer









        $endgroup$



        Like $X_r-2$, $Y_n$ has mean $0$ and variance $2$. The answer is therefore $Phi(sqrt{2})-Phi(frac{-1}{sqrt{2}})approx 0.6816$.







        share|cite|improve this answer












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        answered Dec 8 '18 at 10:27









        J.G.J.G.

        26.3k22541




        26.3k22541






























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