A particle starts at 00 and moves in oneunit independent ste

A particle starts at (0,0) and moves in one-unit independent steps with equal probabilities of 1/4 in each of the four directions: north, south, east, and west. Let S equal the east-west position and T the north-south position after n steps. (a) Define the joint p.m.f. of S and T with n = 3. On a two -dimensional graph, give the probabilities of the joint pmf and the marginal pmfs. (b) What are the marginal distributions of X and Y?

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