The (random) variable X is number of Jingtinglers owned by a randomly selected Who house- hold, and the probability distribution function for X is given in the table below. x P (X = x) 0 0.05 1 0.1 2 0.2 3 0.3 4 0.25 5 0.1 (a) What is the probability that a randomly selected Who household owns at least 3 Jingtin- glers? (b) What is the probability that a randomly selected Who household owns at least 4 Jingtinglers, given that they own more than 2? (c) What are the mean and standard deviation of X? (d) What is the (approximate) probability that the mean number of Jingtinglers in a random sample of 400 Who households is between 2 and 3?