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The random vector (X, Y) is said to be uniformly distributed over a region R in the plane if, for some constant c, its joint density is

( c if (x,y) ∈ R
f(x,y) = { 0 else




Show that 1/c = area of region R.
Suppose that (X, Y) is uniformly distributed over the square centered at (0,0) and with sides of length 2.

1 Answer

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Final answer:

To show that 1/c equals the area of region R for a uniform distribution of a continuous random variable, one must integrate the joint density function over R, and the result should be 1. The constant c is then found to be 1/Area of R. For a square centered at (0,0) with sides of length 2, the constant c is 1/4 since the area of the square is 4.

Step-by-step explanation:

Uniform Distribution in Continuous Random Variables

To solve the mathematical problem completely, we must first understand the uniform distribution related to continuous random variables (RVs). By definition, a continuous random variable, such as (X, Y), uniformly distributed over a region R, implies that the probability of (X, Y) falling within any sub-region of R is proportional to the area of that sub-region. The joint density function f(x, y) for (X, Y) is given by:

f(x, y) = c if (x, y) ∈ R, 0 else

To show that 1/c = area of region R, we integrate the joint density function over the entire region R, which should equal 1 since the total probability must sum up to 1.

The f(x, y) integrated over region R equals:

∫∫_R f(x, y) dxdy = ∫∫_R c dxdy = c × (Area of R) = 1

Hence, we find that c = 1/Area of R. For a square centered at (0,0) with sides of length 2, the area of R is 2· 2 = 4, thus c = 1/4.

The probability density function is uniformly distributed and the graph of the pdf would resemble a rectangle with the height of the rectangle corresponding to the constant c.

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