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# Transformations - Joint and Marginal Probability Mass Function

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Let X1 and X2 have the joint pmf p(x1,x2) = (x1x2)/36 x1=1,2,3 and x2=1,2,3, zero elsewhere. Find first the joint pmf of Y1=X1X2 and Y2=X2, and then find the marginal pmf of Y1.

https://brainmass.com/statistics/probability/transformations-joint-marginal-probability-mass-function-43357

#### Solution Preview

Let X1 and X2 have the joint pmf p(x1,x2) = (x1x2)/36 x1=1,2,3 and x2=1,2,3, zero elsewhere. Find first the joint pmf of Y1=X1X2 and Y2=X2, and then find the marginal pmf of Y1.

Solution.
By given information, we have

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X1 1 2 3
X2
1 1/36 2/36 3/36

2 2/36 ...

#### Solution Summary

This solution is provided in 184 words. It uses a chart and step-by-step equations to find the marginal and joint pdf.

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