SOLUTION: if a family plan to have 4 kids ,. what is the probability that 3 of kids would be girls? how to find the mean and standrad deviation?

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Question 571886: if a family plan to have 4 kids ,. what is the probability that 3 of kids would be girls? how to find the mean and standrad deviation?
Answer by stanbon(75887) About Me  (Show Source):
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if a family plan to have 4 kids ,. what is the probability that 3 of kids would be girls? how to find the mean and standrad deviation?
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Binomial with n = 4 and p(girl) = 1/2
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P(x = 3) = 4C3*(1/2)^3*(1/2) = 4/16 = 1/4
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mean = np 4*1/2 = 2
std = sqrt(npq) = sqrt(2*1/2) = 1
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cheers,
Stan H.
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