X represents the number of defective items drawn.
∴ X can take values 0, 1, 2 or 3
∵ there are total 25 items (20 good + 5 defectives) items
n(S) = total possible ways of selecting 5 items = 25C4
P(X = 0) = P(selecting no defective item)
P(X = 1) = P(selecting 1 defective item and 3 good items)
P(X = 2) = P(selecting 2 defective items and 2 good items)
P(X = 3) = P(selecting 3 defective items and 1 good item)
P(X = 4) = P(selecting 4 defective items and no good item)
Now we have pi and xi.
Following table represents probability distribution of X :