Elementary statistics

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Nine apples, four of which are rotten, are in a refrigerator. Three apples are randomly selected without replacement. Let the random variable x represent the number chosen that are rotten. Construct a table describing the probability distribution, then find the mean and standard deviation for the random variable x.


this is the table

X P(x)

0 0.167
1 0.500
2 0.300
3 0.033

  • Elementary statistics -

    The total number of outcomes is 9C3, because there are nine apples and you are choosing 3 where order doesn't matter.

    P(0) = 5C3 / 9C3

    because there are 5 good apples and you need to choose 3.

    P(1) = 5C2*4C1 / 9C3
    P(2) = 5C1*4C2 / 9C3
    P(3) = 5C0*4C3 / 9C3

  • Elementary statistics -

    THANK YOU SO MUCH I have been stumped on this question for hours on two different occasions, I am so glad you cleared this up for me.

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