Answer:
See pmf of Y below
Step-by-step explanation:
Let's abbreviate the days by using the first letter, W, T, F and S.
The following array shows the possible probabilities for Y.
Since the probabilities are independent Y(a,b) = P(a)*P(b) for any day a,b.
The array shows the pmf of Y, that is, the probability that the number of days <em>beyond TUESDAY</em> (as we are considering W) that it takes for both magazines to arrive after Wednesday equals to or is greater than 0.
computing the probabilities, we get the array
The right way to read Y is Y(row,column). For example, the probability that magazine 1 arrives on Thursday and magazine 2 arrives on Friday is Y(T,F) = 0.0798.