Probability

Question

State which of the following are not the probability distribution of a random variable. Give reasons for your answer.

Y

-1

0

1

P(Y)

0.6

0.1

0.2

Solution

Y	-1	0	1
P(Y)	0.6	0.1	0.2

ΣP(Y) = 0.6 + 0.1 + 0.2 = 0.9 ≠ 1
This is not possible as ΣP(Y) = 1
∴ given distribution is not a probability distribution of a random variable.