Calculating a conditional expectation (probability theory)











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Let $X$ and $Y$ be two random variables with the joint probability density function $f_{xy}(x,y)=(15/4) x y^2$ for $0 < 2 y leq x leq 2$ and $0$ otherwise.



Calculate ${cal E}[X^2+Y^2 leq 1 | X geq 0.5]$










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  • 1




    But you must have tried something. Could you show your work first?
    – StubbornAtom
    Nov 19 at 19:20






  • 1




    I am a beginner... but are you supposed to calculate $E[X^2+Y^2 le 1 | X geq 0.5]$ or $P[X^2+Y^2 le 1 | X ge 0.5]$ I've seen questions that ask to calculate $E[g(X,Y) mid A]$ but not when $g(X,Y)$ is a statement like that. Again I'm a noob
    – HJ_beginner
    Nov 19 at 19:35










  • Hi,thanks for your answer.Iam supposed to calculate expectation not probability and what you mentioned is exactly where i don't understand. I mean expectation of an event conditioned on another event that's the reason i cannot solve this
    – amirkard
    Nov 19 at 20:26















up vote
0
down vote

favorite












Let $X$ and $Y$ be two random variables with the joint probability density function $f_{xy}(x,y)=(15/4) x y^2$ for $0 < 2 y leq x leq 2$ and $0$ otherwise.



Calculate ${cal E}[X^2+Y^2 leq 1 | X geq 0.5]$










share|cite|improve this question




















  • 1




    But you must have tried something. Could you show your work first?
    – StubbornAtom
    Nov 19 at 19:20






  • 1




    I am a beginner... but are you supposed to calculate $E[X^2+Y^2 le 1 | X geq 0.5]$ or $P[X^2+Y^2 le 1 | X ge 0.5]$ I've seen questions that ask to calculate $E[g(X,Y) mid A]$ but not when $g(X,Y)$ is a statement like that. Again I'm a noob
    – HJ_beginner
    Nov 19 at 19:35










  • Hi,thanks for your answer.Iam supposed to calculate expectation not probability and what you mentioned is exactly where i don't understand. I mean expectation of an event conditioned on another event that's the reason i cannot solve this
    – amirkard
    Nov 19 at 20:26













up vote
0
down vote

favorite









up vote
0
down vote

favorite











Let $X$ and $Y$ be two random variables with the joint probability density function $f_{xy}(x,y)=(15/4) x y^2$ for $0 < 2 y leq x leq 2$ and $0$ otherwise.



Calculate ${cal E}[X^2+Y^2 leq 1 | X geq 0.5]$










share|cite|improve this question















Let $X$ and $Y$ be two random variables with the joint probability density function $f_{xy}(x,y)=(15/4) x y^2$ for $0 < 2 y leq x leq 2$ and $0$ otherwise.



Calculate ${cal E}[X^2+Y^2 leq 1 | X geq 0.5]$







probability conditional-expectation






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share|cite|improve this question













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share|cite|improve this question








edited Nov 19 at 19:30









David G. Stork

9,30721232




9,30721232










asked Nov 19 at 19:16









amirkard

12




12








  • 1




    But you must have tried something. Could you show your work first?
    – StubbornAtom
    Nov 19 at 19:20






  • 1




    I am a beginner... but are you supposed to calculate $E[X^2+Y^2 le 1 | X geq 0.5]$ or $P[X^2+Y^2 le 1 | X ge 0.5]$ I've seen questions that ask to calculate $E[g(X,Y) mid A]$ but not when $g(X,Y)$ is a statement like that. Again I'm a noob
    – HJ_beginner
    Nov 19 at 19:35










  • Hi,thanks for your answer.Iam supposed to calculate expectation not probability and what you mentioned is exactly where i don't understand. I mean expectation of an event conditioned on another event that's the reason i cannot solve this
    – amirkard
    Nov 19 at 20:26














  • 1




    But you must have tried something. Could you show your work first?
    – StubbornAtom
    Nov 19 at 19:20






  • 1




    I am a beginner... but are you supposed to calculate $E[X^2+Y^2 le 1 | X geq 0.5]$ or $P[X^2+Y^2 le 1 | X ge 0.5]$ I've seen questions that ask to calculate $E[g(X,Y) mid A]$ but not when $g(X,Y)$ is a statement like that. Again I'm a noob
    – HJ_beginner
    Nov 19 at 19:35










  • Hi,thanks for your answer.Iam supposed to calculate expectation not probability and what you mentioned is exactly where i don't understand. I mean expectation of an event conditioned on another event that's the reason i cannot solve this
    – amirkard
    Nov 19 at 20:26








1




1




But you must have tried something. Could you show your work first?
– StubbornAtom
Nov 19 at 19:20




But you must have tried something. Could you show your work first?
– StubbornAtom
Nov 19 at 19:20




1




1




I am a beginner... but are you supposed to calculate $E[X^2+Y^2 le 1 | X geq 0.5]$ or $P[X^2+Y^2 le 1 | X ge 0.5]$ I've seen questions that ask to calculate $E[g(X,Y) mid A]$ but not when $g(X,Y)$ is a statement like that. Again I'm a noob
– HJ_beginner
Nov 19 at 19:35




I am a beginner... but are you supposed to calculate $E[X^2+Y^2 le 1 | X geq 0.5]$ or $P[X^2+Y^2 le 1 | X ge 0.5]$ I've seen questions that ask to calculate $E[g(X,Y) mid A]$ but not when $g(X,Y)$ is a statement like that. Again I'm a noob
– HJ_beginner
Nov 19 at 19:35












Hi,thanks for your answer.Iam supposed to calculate expectation not probability and what you mentioned is exactly where i don't understand. I mean expectation of an event conditioned on another event that's the reason i cannot solve this
– amirkard
Nov 19 at 20:26




Hi,thanks for your answer.Iam supposed to calculate expectation not probability and what you mentioned is exactly where i don't understand. I mean expectation of an event conditioned on another event that's the reason i cannot solve this
– amirkard
Nov 19 at 20:26















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