SOLUTION: please help me solve this question. a group of students have three desktop computers and three laptop computers. they want to select two computers at random for a course project.

Question 933559: please help me solve this question.
a group of students have three desktop computers and three laptop computers. they want to select two computers at random for a course project. Let X be the number of laptop computers in the selection.how many ways can the students select two computers from six? what is the probability of selecting X=2 laptop computers? construct a probability distribution table for X? find the variance of X?
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
a group of students have 3 desktop computers and 3 laptop computers. they want to select 2 computers at random for a course project.
Let X be the number of laptop computers in the selection.
how many ways can the students select two computers from six? 6C2 = 15
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what is the probability of selecting X=2 laptop computers?
P(x = 2) = 3C2/6C2 = 3/15 = 1/5
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construct a probability distribution table for X?
P(x = 0) = (3C0*3C2)/6C2 = (1*3)/6C2 = 1/5
P(x = 1) = (3C1*3C1)/6C2) = 9/15 = 3/5
P(x = 2) = (3C2)(3C0)/6C2 = 1/5
find the variance of X?
Ans: 2/3
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Cheers,
Stan H.
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