Question

give the following probability distribution, find P(X=3)

X 1 2 3 4 5
P(x) 0.4 0.1 0.15 0.2

Answer 1

Hint:
In a discrete probability distribution, the sum of the probabilities of all possible outcomes equals 1.
Probability of unlisted outcomes are assumed to be zero.

Answer 2

.15

Answer 3

Exactly, since altogether the probabilities add up to 1.0,
then 1-(0.4+0.1+0.15+0.2)=0.15.