Question 926821
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Hi
two chosen...
expected value is the SUM of nP(n) where n is 0,1,2
.....
for example
five children: 3G, 2B
Determine the expected value of the number of girls who will be selected
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n  P(n)
0  1/10    P(both boys) = {{{(2/5)(1/4)}}}
1  3/5     P(one girl) = {{{(3/5)(2/4) + (2/5)(3/4) = 12/20}}}
2  <u>3/10</u>    P(two girls) = {{{(3/5)(2/4) = 6/20}}}
    1
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Exp = 0(1/10) + 1(3/5) + 2(3/10) = 6/10 + 6/10 = 12/10) = 1.2  0r 1 girl