Probability of normal distribution larger than half normal distribution












0












$begingroup$


I am pretty new to normal distribution and stuck on this question:



X ~ N(0, 1)



Y ~ N(0, 1)



X independent of Y



What is the probability of P(X>|2Y|)?



I know linear combination of normal distribution is normal distribution but what about linear combination of normal distribution and absolute value of normal distribution?










share|cite|improve this question









$endgroup$

















    0












    $begingroup$


    I am pretty new to normal distribution and stuck on this question:



    X ~ N(0, 1)



    Y ~ N(0, 1)



    X independent of Y



    What is the probability of P(X>|2Y|)?



    I know linear combination of normal distribution is normal distribution but what about linear combination of normal distribution and absolute value of normal distribution?










    share|cite|improve this question









    $endgroup$















      0












      0








      0





      $begingroup$


      I am pretty new to normal distribution and stuck on this question:



      X ~ N(0, 1)



      Y ~ N(0, 1)



      X independent of Y



      What is the probability of P(X>|2Y|)?



      I know linear combination of normal distribution is normal distribution but what about linear combination of normal distribution and absolute value of normal distribution?










      share|cite|improve this question









      $endgroup$




      I am pretty new to normal distribution and stuck on this question:



      X ~ N(0, 1)



      Y ~ N(0, 1)



      X independent of Y



      What is the probability of P(X>|2Y|)?



      I know linear combination of normal distribution is normal distribution but what about linear combination of normal distribution and absolute value of normal distribution?







      probability normal-distribution






      share|cite|improve this question













      share|cite|improve this question











      share|cite|improve this question




      share|cite|improve this question










      asked Dec 29 '18 at 2:10









      Ziyue JinZiyue Jin

      31




      31






















          1 Answer
          1






          active

          oldest

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          2












          $begingroup$

          You can view $(X,Y)$ as a random point on the plane $mathbb{R}^2$. The joint distribution is the standard bivariate normal distribution and is radially symmetric about the origin.



          Plot the region consisting of pairs $(x,y)$ satisfying $x > |2y|$; you will find this is an infinite cone (an infinite slice of pizza or pie, if you will) with vertex at the origin. By the symmetry mentioned above, the probability of the random vector $(X,Y)$ being in this slice is equal to the relative angle of the slice (relative to a full turn, i.e. $2pi$ radians or $360$ degrees).






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Sorry, I don't understand why it is an infinite cone... Is there any mathematical way to calculate this probability?
            $endgroup$
            – Ziyue Jin
            Dec 29 '18 at 5:47










          • $begingroup$
            @ZiyueJin "I don't understand why it is an infinite cone..." Did you plot the region of interest? It might help you understand why it is a cone...
            $endgroup$
            – Did
            Dec 29 '18 at 6:33










          • $begingroup$
            Should any region fall within 1? Because the variance is 1?
            $endgroup$
            – Ziyue Jin
            Dec 29 '18 at 6:35










          • $begingroup$
            This explanation really helps me understand what happened but I still want a solution related to integral over PDF.
            $endgroup$
            – Ziyue Jin
            Dec 29 '18 at 6:36










          • $begingroup$
            "I still want a solution related to integral over PDF" Why? Sorry but this is absurd.
            $endgroup$
            – Did
            Dec 29 '18 at 11:24











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          1 Answer
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          1 Answer
          1






          active

          oldest

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          active

          oldest

          votes






          active

          oldest

          votes









          2












          $begingroup$

          You can view $(X,Y)$ as a random point on the plane $mathbb{R}^2$. The joint distribution is the standard bivariate normal distribution and is radially symmetric about the origin.



          Plot the region consisting of pairs $(x,y)$ satisfying $x > |2y|$; you will find this is an infinite cone (an infinite slice of pizza or pie, if you will) with vertex at the origin. By the symmetry mentioned above, the probability of the random vector $(X,Y)$ being in this slice is equal to the relative angle of the slice (relative to a full turn, i.e. $2pi$ radians or $360$ degrees).






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Sorry, I don't understand why it is an infinite cone... Is there any mathematical way to calculate this probability?
            $endgroup$
            – Ziyue Jin
            Dec 29 '18 at 5:47










          • $begingroup$
            @ZiyueJin "I don't understand why it is an infinite cone..." Did you plot the region of interest? It might help you understand why it is a cone...
            $endgroup$
            – Did
            Dec 29 '18 at 6:33










          • $begingroup$
            Should any region fall within 1? Because the variance is 1?
            $endgroup$
            – Ziyue Jin
            Dec 29 '18 at 6:35










          • $begingroup$
            This explanation really helps me understand what happened but I still want a solution related to integral over PDF.
            $endgroup$
            – Ziyue Jin
            Dec 29 '18 at 6:36










          • $begingroup$
            "I still want a solution related to integral over PDF" Why? Sorry but this is absurd.
            $endgroup$
            – Did
            Dec 29 '18 at 11:24
















          2












          $begingroup$

          You can view $(X,Y)$ as a random point on the plane $mathbb{R}^2$. The joint distribution is the standard bivariate normal distribution and is radially symmetric about the origin.



          Plot the region consisting of pairs $(x,y)$ satisfying $x > |2y|$; you will find this is an infinite cone (an infinite slice of pizza or pie, if you will) with vertex at the origin. By the symmetry mentioned above, the probability of the random vector $(X,Y)$ being in this slice is equal to the relative angle of the slice (relative to a full turn, i.e. $2pi$ radians or $360$ degrees).






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Sorry, I don't understand why it is an infinite cone... Is there any mathematical way to calculate this probability?
            $endgroup$
            – Ziyue Jin
            Dec 29 '18 at 5:47










          • $begingroup$
            @ZiyueJin "I don't understand why it is an infinite cone..." Did you plot the region of interest? It might help you understand why it is a cone...
            $endgroup$
            – Did
            Dec 29 '18 at 6:33










          • $begingroup$
            Should any region fall within 1? Because the variance is 1?
            $endgroup$
            – Ziyue Jin
            Dec 29 '18 at 6:35










          • $begingroup$
            This explanation really helps me understand what happened but I still want a solution related to integral over PDF.
            $endgroup$
            – Ziyue Jin
            Dec 29 '18 at 6:36










          • $begingroup$
            "I still want a solution related to integral over PDF" Why? Sorry but this is absurd.
            $endgroup$
            – Did
            Dec 29 '18 at 11:24














          2












          2








          2





          $begingroup$

          You can view $(X,Y)$ as a random point on the plane $mathbb{R}^2$. The joint distribution is the standard bivariate normal distribution and is radially symmetric about the origin.



          Plot the region consisting of pairs $(x,y)$ satisfying $x > |2y|$; you will find this is an infinite cone (an infinite slice of pizza or pie, if you will) with vertex at the origin. By the symmetry mentioned above, the probability of the random vector $(X,Y)$ being in this slice is equal to the relative angle of the slice (relative to a full turn, i.e. $2pi$ radians or $360$ degrees).






          share|cite|improve this answer









          $endgroup$



          You can view $(X,Y)$ as a random point on the plane $mathbb{R}^2$. The joint distribution is the standard bivariate normal distribution and is radially symmetric about the origin.



          Plot the region consisting of pairs $(x,y)$ satisfying $x > |2y|$; you will find this is an infinite cone (an infinite slice of pizza or pie, if you will) with vertex at the origin. By the symmetry mentioned above, the probability of the random vector $(X,Y)$ being in this slice is equal to the relative angle of the slice (relative to a full turn, i.e. $2pi$ radians or $360$ degrees).







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Dec 29 '18 at 2:31









          angryavianangryavian

          42.2k23481




          42.2k23481












          • $begingroup$
            Sorry, I don't understand why it is an infinite cone... Is there any mathematical way to calculate this probability?
            $endgroup$
            – Ziyue Jin
            Dec 29 '18 at 5:47










          • $begingroup$
            @ZiyueJin "I don't understand why it is an infinite cone..." Did you plot the region of interest? It might help you understand why it is a cone...
            $endgroup$
            – Did
            Dec 29 '18 at 6:33










          • $begingroup$
            Should any region fall within 1? Because the variance is 1?
            $endgroup$
            – Ziyue Jin
            Dec 29 '18 at 6:35










          • $begingroup$
            This explanation really helps me understand what happened but I still want a solution related to integral over PDF.
            $endgroup$
            – Ziyue Jin
            Dec 29 '18 at 6:36










          • $begingroup$
            "I still want a solution related to integral over PDF" Why? Sorry but this is absurd.
            $endgroup$
            – Did
            Dec 29 '18 at 11:24


















          • $begingroup$
            Sorry, I don't understand why it is an infinite cone... Is there any mathematical way to calculate this probability?
            $endgroup$
            – Ziyue Jin
            Dec 29 '18 at 5:47










          • $begingroup$
            @ZiyueJin "I don't understand why it is an infinite cone..." Did you plot the region of interest? It might help you understand why it is a cone...
            $endgroup$
            – Did
            Dec 29 '18 at 6:33










          • $begingroup$
            Should any region fall within 1? Because the variance is 1?
            $endgroup$
            – Ziyue Jin
            Dec 29 '18 at 6:35










          • $begingroup$
            This explanation really helps me understand what happened but I still want a solution related to integral over PDF.
            $endgroup$
            – Ziyue Jin
            Dec 29 '18 at 6:36










          • $begingroup$
            "I still want a solution related to integral over PDF" Why? Sorry but this is absurd.
            $endgroup$
            – Did
            Dec 29 '18 at 11:24
















          $begingroup$
          Sorry, I don't understand why it is an infinite cone... Is there any mathematical way to calculate this probability?
          $endgroup$
          – Ziyue Jin
          Dec 29 '18 at 5:47




          $begingroup$
          Sorry, I don't understand why it is an infinite cone... Is there any mathematical way to calculate this probability?
          $endgroup$
          – Ziyue Jin
          Dec 29 '18 at 5:47












          $begingroup$
          @ZiyueJin "I don't understand why it is an infinite cone..." Did you plot the region of interest? It might help you understand why it is a cone...
          $endgroup$
          – Did
          Dec 29 '18 at 6:33




          $begingroup$
          @ZiyueJin "I don't understand why it is an infinite cone..." Did you plot the region of interest? It might help you understand why it is a cone...
          $endgroup$
          – Did
          Dec 29 '18 at 6:33












          $begingroup$
          Should any region fall within 1? Because the variance is 1?
          $endgroup$
          – Ziyue Jin
          Dec 29 '18 at 6:35




          $begingroup$
          Should any region fall within 1? Because the variance is 1?
          $endgroup$
          – Ziyue Jin
          Dec 29 '18 at 6:35












          $begingroup$
          This explanation really helps me understand what happened but I still want a solution related to integral over PDF.
          $endgroup$
          – Ziyue Jin
          Dec 29 '18 at 6:36




          $begingroup$
          This explanation really helps me understand what happened but I still want a solution related to integral over PDF.
          $endgroup$
          – Ziyue Jin
          Dec 29 '18 at 6:36












          $begingroup$
          "I still want a solution related to integral over PDF" Why? Sorry but this is absurd.
          $endgroup$
          – Did
          Dec 29 '18 at 11:24




          $begingroup$
          "I still want a solution related to integral over PDF" Why? Sorry but this is absurd.
          $endgroup$
          – Did
          Dec 29 '18 at 11:24


















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