1. Consider the experiment of tossing a coin. Heads appear about once out of every three tosses. If this experiment is repeated, what is the probability of the event that heads appear exactly twice during the first five tosses? 2. Two boys and two girls enter a music hall and take four seats at random in a row. What is the probability that the girls take the two end seats? 3. Let (X, Y, Z) be a trivariate r.v., where X, Y, and Z are independent and each has a uniform distribution over (0, 1). Compute P(X2Y2 Z).