Take the 2-minute tour ×
Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

Let $(X,Y,Z)$ be a continuous random vector with joint density $$ f_{(X,Y,Z)}(x,y,z) = 6e^{-x-y-z},\quad 0 < x < y < z. $$

What is the marginal density of $X,Y$ and $Z$?

I have calculated $f_X(x)$ here. I have calculated $f_Y(y)$ here. I have calculated $f_Z(z)$ here.

Is this right?

share|improve this question
    
What kind of comprehension do you try to achieve by plugging these into W|A? If your test is Plug these into W|A and write down the result, OK. Otherwise, I fail to see the point. (Strictly speaking, note that you have calculated nothing, W|A has.) –  Did Sep 24 '12 at 11:33
    
I'm using Wolfram Alpha because I'm not familiar with writing formatted mathematical notation. The computation is easy; I'm more concerned with whether I set up the boundaries of the integrals correctly. –  idealistikz Sep 24 '12 at 19:54

1 Answer 1

up vote 0 down vote accepted

Those are correct, I suggest you integrate on your own(pencil and paper) since you will be doing so for your tests.

share|improve this answer
    
I did, but I posted the links to Wolfram because I am unfamiliar with writing mathematical notation on this site. –  idealistikz Sep 24 '12 at 10:58

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.