How to Find the PDF for a Uniform Distribution on a Disc?

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SUMMARY

The probability density function (pdf) for a uniform distribution on a disc of radius 1 is given by f(x,y) = 1/π for x² + y² ≤ 1 and 0 otherwise. This formulation ensures that the total probability integrates to 1 over the area of the disc, which is π. The initial incorrect attempt at the pdf, f_{xy} = (x² + y²)/π, does not represent a uniform distribution. The correct approach involves recognizing the uniform nature of the distribution across the area of the disc.

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Homework Statement



\D = \{(x,y) \in \mathbb{R}^2 | x^2 + y^2 \leq 1\} i.e. a disc or radius 1.
Write down the pdf f_{xy} for a uniform distribution on the disc.

Homework Equations





The Attempt at a Solution



f_{xy} = \frac{(x^2 + y^2)}{\pi} \mbox{for} x^2 + y^2 \leq 1 0 otherwise
as the area of the disc pi and to make it uniform you divide by pi so the probability integrates to 1
 
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Hmmm...

f_{xy} = \frac{(x^2 + y^2)}{\pi}

Doesn't look very uniform to me:wink:
 
i think i got it: its <br /> f(x,y)_{xy} = \left\{ \begin{array}{rl}<br /> \frac{1}{\pi} &amp;\mbox{for } x^2 + y^2 \leq 1\\<br /> 0 &amp;\mbox{otherwise}<br />

thanks
 
Last edited:
Looks good to me!:approve:
 
I am doing a some practice questions for stats and i tried to integrate this to get 1 but i can't so what are the appropriate limits and how would i go about finding the marginal distribution of x and y? Thanks
 

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