ok, assuming the equation might looks like this 500!/490!10!, can anyone help? I can cancel out the 490!, and reduce some numbers but I still find what i have left to be too high, anyone with any thoughts?

- Thread starter anasylum
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ok, assuming the equation might looks like this 500!/490!10!, can anyone help? I can cancel out the 490!, and reduce some numbers but I still find what i have left to be too high, anyone with any thoughts?

Given a population of N items having k successes and N-k failures, the probability of selecting a sample of size n that has x successes and n-x failures is given by:

\(\displaystyle \frac{C(k,x)C(N-k,n-x)}{C(N,n)}\)

Can you finish using the formula?.

You are drawing 10 from the 500 and finding the probability that all of those are defects. So, you are choosing 0 of the 480 good ones and 10 of the 20 bad ones. Intuitively, I would say the probability is mighty low.

So, you have(from the formula):

\(\displaystyle \frac{C(480,0)C(20,10)}{C(500,10)}\)