A Web site uses ads to route visitors to one of four land- ing pages. The probabilities for each landing page are equal.. Consider 20 independent visitors and let the random variables W. X, Y, and Z denote the number of visitors routed to each page. Calculate the following:

(a) P(W=5, X=5,Y=5,Z=5) (b)P(W 5,X=5,Y=5)

(c) PW 7.X 7,Y=6|Z=3)

(d) PW=7.X=7,Y=3|Z=3)

(e) PW2) (1) E(W) (g) AW-5,X-5) (h)P(W=5|x=5)