A numerical value assigned to the outcome of an experiment is called a random variable X. The correspondence between the values X takes and their probabilities is called a probability distribution.
Example ① If X is the number shown when a die is rolled once, find the probability distribution of X.
Solution:Each of X=1,2,3,4,5,6 has probability 1/6.
Solution:Each of X=1,2,3,4,5,6 has probability 1/6.
Key Point
- The probabilities must always sum to 1
Practice Problems
- Find the probability distribution of X, the number of heads obtained with two coins.
Solutions and Explanations
- Solution:P(X=0)=1/4, P(X=1)=1/2, P(X=2)=1/4