committee of 3 people us to be formed using 2 girls and 5 boys. let X be the number of girls on the committee. what is var (x)

Question

Finite question

Answer 1

Set up a probability distribution table:

 

X    p(x)     x(p(x))     x²      px²

---------------------------------------

0

1

2

 

Calculate probability of each (column 2); add up column 3 to get mean;

 

use formula for var(x)= (add up column 5) - mean²

 

 

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