A library subscribes to two different weekly news magazines, each of which is supposed to arrive in Wednesday�s mail. In actuality, each one may arrive on Wednesday, Thursday, Friday, or Saturday. Suppose the two arrive independently of one another, and for each one P(Wed.) = .3, P(Thurs.) = .4, P(Fri.) = .2, and P(Sat.) = .1. Let Y = the number of days beyond Wednesday that it takes for both magazines to arrive (so possible Y values are 0, 1, 2, or 3). Compute the pmf of Y.

P(Y = 0) = 0.09

P(Y = 1) = 0.4

P(Y = 2) = 0.32

P(Y = 3) = 0.19

Step-by-step explanation:

Let the events be:

Wednesday

Thursday

Friday

Saturday

Their corresponding probabilities are

Since = number of days beyond Wednesday that it takes for both magazines to arrive(so possible values are 0, 1, 2 or 3)

The possible number of outcomes are therefore

The values associated for each of the outcomes are as follows:

The probability mass function of is,

d. you cannot tell because there are no values shown.