I am a college undergrad just starting my preparations for my P/1 test. The following question was in a book I am using to study:

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Consider a random variable X whose probability mass function is given by

p(x) = 0.2 , x = −1

0.3 , x = 0

0.1 , x = 0.2

0.1 , x = 0.5

0.3 , x = 4

0 otherwise

Find E(p(x)).

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My method was to multipy all of the probabilities by the possible outcomes, .2*-1 + .3*0 + .1*.2 + .1*.5 + .3*4 and i got 1.07. The solution given was .24 and I also had arrived at a different answer in a similar question involving expected values of cdfs. I'm pretty sure there is something fundamental I am missing here. Someone please help! THANKS!

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Consider a random variable X whose probability mass function is given by

p(x) = 0.2 , x = −1

0.3 , x = 0

0.1 , x = 0.2

0.1 , x = 0.5

0.3 , x = 4

0 otherwise

Find E(p(x)).

------------------------------------------------------------------------

My method was to multipy all of the probabilities by the possible outcomes, .2*-1 + .3*0 + .1*.2 + .1*.5 + .3*4 and i got 1.07. The solution given was .24 and I also had arrived at a different answer in a similar question involving expected values of cdfs. I'm pretty sure there is something fundamental I am missing here. Someone please help! THANKS!

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