A real estate salesperson has three properties listed for 40k, 100k, and 80k. He thinks that the probability of selling the first listing in November is .5. The probabilities of selling the other two listings in November are 1/4 and 3/4 respectively. Determine the probability mass function of the salesperson's November sales (in $). What is the probabiity that his sales for November will be less than 100k? Find the mean and standard deviation of the November sales.