.
Write the probability distribution of a random variable R representing the number
of red balls when 3 balls are drawn in succession without replacement from a jar
containing 4 reds and 5 blue balls.
~~~~~~~~~~~~~~~~~~~
There are 4 possible values for R : they are 0, 1, 2 and 3.
Notice that the total balls is 4 + 5 = 9.
R = 0 : P(0) = = = = .
R = 1 : P(1) = = = = .
R = 2 : P(2) = = = = .
R = 3 : P(3) = = = = .
I intentionally left these fractions in this form, not fully reduced.
You can easily check that the sum of all probabilities equals to 1.
Solved.