Suppose that a box contains 40 red balls 30 black balls and
     Suppose that a box contains 40 red balls, 30 black balls, and 20 yellow balls. A sample of five balls is drawn without replacement. Let x = number of red, y = number of black and z = number of yellow.  Find the probability that x = 1, y = 1, and z=3.  Find the joint pdf of X and Z.  Suppose that X and Y are continuous random variables with joint pdf  Find the marginal pdf\'s of X and Y.  Are X and Y independent?  Find P(X > 3).  Find P(X > Y).  Find P(X + Y > 3).  Suppose that X and Y are continuous random variables with CDF  Find the joint pdf, f(x,y).  P(X  
  
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