Posted by **Kim** on Tuesday, August 20, 2013 at 4:35pm.

The random variable x represents the number of boys in a family with three children.

Assuming that births of boys and girls are equally likely, find the mean and standard

deviation for the random variable x.

- statistic -
**MathMate**, Wednesday, August 21, 2013 at 8:17am
This is a binomial distribution with parameters

n=3 (number of trials in the experiment)

p=1/2 (probability of boys, X)

q=1-p (probability of girls)

For a random variable X with a binomial distribution (n,p,q), then

E(x)=μ=np

σ²=npq

where σ=standard deviation (of population)

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