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January 9th, 2011, 10:17 AM  #1 
Newbie Joined: Jan 2011 Posts: 5 Thanks: 0  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.

January 9th, 2011, 01:01 PM  #2 
Newbie Joined: Jan 2011 Posts: 22 Thanks: 0  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...

January 9th, 2011, 02:05 PM  #3 
Newbie Joined: Jan 2011 Posts: 5 Thanks: 0  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?

January 9th, 2011, 10:53 PM  #4 
Newbie Joined: Jan 2011 Posts: 5 Thanks: 0  Re: Probability of drawing one company
1 : 61 601 111 258 ?

January 10th, 2011, 12:16 AM  #5 
Newbie Joined: Jan 2011 Posts: 22 Thanks: 0  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? 
January 10th, 2011, 01:24 PM  #6 
Newbie Joined: Jan 2011 Posts: 5 Thanks: 0  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^(nk); where p=see row above, q=(1p), k=8 and n=10 
January 10th, 2011, 01:33 PM  #7 
Newbie Joined: Jan 2011 Posts: 5 Thanks: 0  Re: Probability of drawing one company
Cimoo you are totaly right !!! 1/1.624*E11= 61 576 354 680 (because you used just 3 decimal numbers) 

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