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Probability Question
Based on the attached table, what is the probability that if two people are selected at random that they both of them are nonsmoking females
What I did was
(140/200)(90/200)(139/199)(89/199)
but that was incorrect
can someone tell me the accurate way to do this?
thank you!

$\displaystyle \displaystyle\left( {\frac{{70}}{{200}}} \right)\left( {\frac{{69}}{{199}}} \right)$
Do you understand why?

$\displaystyle \frac{\left({70 \atop 2}\right)}{\left({200\atop 2}\right)}$

Quote:
Originally Posted by
MathoMan 70c2/200c2
@MathoMan
Here is a comment: those two answers are equal.