Determine whether each of the distributions given below represents a probability distribution. Justify your answer.

Question

(A)

x 1 2 3 4
P(x) 1/5 5/12 1/3 1/6




(B)

x 3 6 8
P(x) 0.2 2/5 0.3



(C)

x 20 35 40 50
P(x) 0.3 -0.1 0.5 0.3

Answer 1

Here are some hints:

P(x) must add up to 1. Also, all numerical values for P(x) must be between 0 and 1. These two properties need to be satisfied for these problems to be considered a probability distribution.

I'll let you take it from here. (Here is another hint: only one of these problems fits the criteria.)