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

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

(A)
x
1
2
3
4

P(x)
1/12
5/12
1/3
1/12




(B)
x
3
6
8

P(x)
2/10
.5
1/5




(C)
x
20
35
40
50

P(x)
0.4
-0.2
0.5
0.3

It's a probability distribution only if P(x) ≥ 0 for all x and the sum of all P(x) is 1.

A) No, the sum is 11/12

B) No, the sum is 9/10

C) No, one of the P(x) is negative