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












1














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
















1














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






















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














1












1








1







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













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 at 10:15









Kriti Arora

396




396












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


















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
















@Damandeep Its an online course in probability and stats
– Kriti Arora
Dec 14 at 11:43




@Damandeep Its an online course in probability and stats
– Kriti Arora
Dec 14 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 Answer
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    1 Answer
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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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      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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        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












        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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        answered Dec 8 at 10:27









        J.G.

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