Question 237694: From a group of 3 men and 4 women, a delegation of 2 is selected. What is the expected number of men in the delegation???
I answered (which I am not at all sure about)
P(men) = (3)(2) = 6
P(women) = (4)(2) = 8
6/8 = 3/4
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! From a group of 3 men and 4 women, a delegation of 2 is selected. What is the expected number of men in the delegation???
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Let random variable "x" be the number of men in the delegation.
x values are 0 , 1 , 2, 3
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The corresponding probabilities are:
P(x=0) = 3C2/7C2 = 3/21
P(x=1) = 3C1*4C1/7C2 = 12/21
P(x=2) = 3C2/7C2 = 3/21
P(x=3) = 3C2/7C2 = 3/21
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To get the expected value, multiply each random number value
by its probability and add.
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E(x) = [0*3 + 1*12 + 2*3 + 3*3]/21
E(x) = 27/21 = 1.29
You can expect there will be 1.29 men in the delegation.
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Cheers,
stan H.
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