the problem is below

(2) A salesman has scheduled two appointments to sell encyclopedias. His rst appointment will lead to a sale with probability 0.4, and his second will lead independently to a sale with probability 0.6. Any sale made is equally likely to be either for the deluxe model, which costs $2000, or the standard model, which costs $1000. (a) Determine the probability mass function of X, the total dollar value of all sales. (b) Determine the expectation and the standard deviation of X