Chapter 4 Joint Distribution & Function of rV
Joint Discrete Distribution Definition
Joint discrete CDF
Example for joint distributions Consider the following table: Using the table, we have Y=0 Y=3 Y=4 X=5 1/7 1/7 1/7 3/7 X=8 3/7 0 1/7 4/7 4/7 1/7 2/7 pXpX pYpY
The Marginal PDF
Example : Air Conditioner Maintenance –A company that services air conditioner units in residences and office blocks is interested in how to schedule its technicians in the most efficient manner –The random variable X, taking the values 1,2,3 and 4, is the service time in hours –The random variable Y, taking the values 1,2 and 3, is the number of air conditioner units
Expected Values for Jointly Distributed Random Variables Let X and Y be discrete random variables with joint probability density function p(x, y). Let the sets of values of X and Y be A and B, resp. We define E(X) and E(Y) as For the random variables X and Y from the previous slide example,
Joint p.d.f Joint cdf Y= number of units X=service time Find E[X] and E[Y] !!
Previously Example –Marginal p.d.f of X –Marginal p.d.f of Y
Joint continuous distribution
Th
Ex a. Then find the joint CDF !
The Marginal Continuous PDF FindFrom previously example
Ex
Independent rV
Conditional pdf
Joint MGF
Group Discuss the exercise bellow ! BAIN, page : 166- No 7, 9, 21, 30 Time : 30’