Thread: joint distribution #2

I dont understand why the joint distribution of (2,1) two computers and one printer = (2 x 0.6 x 0.4)(0.2). Where does the 2 come from? My teacher bc there are two ways to do it but that didnt make any sense to me. I thought it would be (0.6 x 0.4)(0.2) bc 0.2= 2 comps sold 0.4= 1 printer sold and 0.6=1-0.4 for the comp that was sold and printer not sold.


2. Suppose that the number of computers sold in exercise 1 has the distribution, P(0)=0.5, P(1)=0.3, P(2)=0.2. Computers are sold at $600 a piece. Also, every customer who buys a computer may also buy a printer with probability 0.4.


(b) Find the marginal distribution of the number of printers sold.