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January 9th, 2011, 10:17 AM   #1
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Probability of drawing one company

You have 214 companies in the database. What is the the probability of drawing 8 times one same company, among 6 companies you are drawing in each drawing, in 10 drawings.
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January 9th, 2011, 01:01 PM   #2
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Re: Probability of drawing one company

You need to clarify the question, the word 'drawing' appears 4 times there, I don't really understand what you're asking...
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January 9th, 2011, 02:05 PM   #3
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Re: Probability of drawing one company

What is the probability of drawing one same company among 6 drawn companies in 8 drawings out of 10. In each drawing you are drawing 6 companies out of the 214 companies. Is this more understandable now?
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January 9th, 2011, 10:53 PM   #4
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Re: Probability of drawing one company

1 : 61 601 111 258 ?
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January 10th, 2011, 12:16 AM   #5
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Re: Probability of drawing one company

I still don't understand the problem, or what "1 : 61 601 111 258 ?" is for, but I'll tell you how to solve what I think the problem is.

P(same company) = 1/214 * 6 = 6/214 (because you have 6 chances from each draw)
P(Žsame company) = 208/214

Using binomial distribution:



Pretty unlikely, as you'd expect...

Can anyone else confirm that?
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January 10th, 2011, 01:24 PM   #6
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Re: Probability of drawing one company

Agree with p=1/214*6

Expression for probability of independent repeated events is P=(n above k)*p^k*q^(n-k); where p=see row above, q=(1-p), k=8 and n=10
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January 10th, 2011, 01:33 PM   #7
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Re: Probability of drawing one company

Cimoo you are totaly right !!!

1/1.624*E-11= 61 576 354 680 (because you used just 3 decimal numbers)
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