Quick Problem: Binomial Probability Distribution

[DavidB]

Just a very quick problem that's been annoying me (very much a math lightweight) for a few days:

How do you compute the probability of having 2 boys from a family of 10 children? (Assuming, of course, that boys and girls are the only possible offspring, no hermaphrodites!)

Thank you.

 

[galactus]

$\displaystyle C(10,2)(.5)^{2}(.5)^{8}$

Or we can do it this way:

$\displaystyle \frac{10!}{8!2!}\cdot\left(\frac{1}{2}\right)^{10}$

which is basically the same thing. See why?.

 

[DavidB]

Thank you for your effort.

Do I see why? Well....I'm working on it!

Thank you again. Very prompt and (I'm assuming) correct reply. FreeMathHelp.com is on my "nice" list!