Problems in Probability

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Fall 2011 Strategic Practice 8: Section 2 (Transformations) - Question 2
Let and let be independent of U. Define and . Find the joint PDF of (X, Y). Are they independent? What are their marginal distributions?
Solution: Using Jacobians to go from the joint pdf of U, T to that of X, Y, we see the latter factors into a function of x times a function of y, so X and Y are independent, and they each have the N(0, 1) distribution. Thus, X and Y are i.i.d. standard Normal r.v.s; this result is called the Box-Muller method for generating Normal r.v.s.
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