# probability

• May 4th 2010, 09:59 AM
chutiya
probability
an urn contains 10 marbles of the same size and weight of which 2 are red, 5 are yellow, and 3 are green. n=5 marbles are drawin, with replacement from the urn. calculate the probability that 1 red, 2 yellow, and 2 green marbles are obtained!

I am totally stumped on this question! can anyone help?
• May 4th 2010, 10:02 AM
harish21
Quote:

Originally Posted by chutiya
an urn contains 10 marbles of the same size and weight of which 2 are red, 5 are yellow, and 3 are green. n=5 marbles are drawin, with replacement from the urn. calculate the probability that 1 red, 2 yellow, and 2 green marbles are obtained!

I am totally stumped on this question! can anyone help?

Probability = $\displaystyle \frac{5!}{1!\times 2! \times 2!} \times {\left(\frac{2}{10}\right)}\times {\left(\frac{5}{10}\right)}^2 \times {\left(\frac{3}{10}\right)}^2$
• May 4th 2010, 04:13 PM
matheagle
that's correct
it's multinomial since you are sampling with replacement
it would be hypergeometric if you didn't replace the marbles