Mario
Lv 5
Mario asked in Science & MathematicsMathematics · 6 years ago

Find the constant k from the joint probability function of two random variables?

The joint PF of two discrete RVs X and Y is given by:

PXY(x,y) = k(2x+y) x=1,2; y=1,2

= 0 otherwise

How do I find the constant k?

I got k to be 1/18, but I don't know if that's right

thanks

1 Answer

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  • kb
    Lv 7
    6 years ago
    Favorite Answer

    Remember that the sum of all (nonzero) probabilities should equal 1.

    So, we need

    P(1, 1) + P(1, 2) + P(2, 1) + P(2, 2) = 1

    ==> 3k + 4k + 5k + 6k = 1

    ==> k = 1/18.

    I hope this helps!

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