SOLUTION: 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

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Question 1191263: 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.
Answer by ikleyn(52794) About Me  (Show Source):
You can put this solution on YOUR website!
.
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.
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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) = %28C%5B5%5D%5E3%2AC%5B4%5D%5E0%29%2FC%5B9%5D%5E3 = %2810%2A1%29%2F84 = 10%2F84 = 5%2F42.


R = 1 :  P(1) = %28C%5B5%5D%5E2%2AC%5B4%5D%5E1%29%2FC%5B9%5D%5E3 = 10%2A4%29%2F84 = 40%2F84 = 20%2F42.


R = 2 :  P(2) = %28C%5B5%5D%5E1%2AC%5B4%5D%5E2%29%2FC%5B9%5D%5E3 = 5%2A6%29%2F84 = 30%2F84 = 15%2F42.


R = 3 :  P(3) = %28C%5B5%5D%5E0%2AC%5B4%5D%5E3%29%2FC%5B9%5D%5E3 = 1%2A4%29%2F84 = 4%2F84 = 2%2F42.



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.