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Topic: Picking n numbers at random
Replies: 8   Last Post: Mar 13, 2012 2:06 AM

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 Frederick Williams Posts: 2,166 Registered: 10/4/10
Re: Picking n numbers at random
Posted: Mar 11, 2012 2:02 PM

José Carlos Santos wrote:
>
> Hi all,
>
> I suppose that this is an easy problem, but I don't know how to solve
> it. Let _n_ be an integer greater than 1. Suppose that you pick a number
> at random from 1 to _n_ and that you do that again and again, your goal
> being to have picked each number from 1 to _n_ at least once. How many
> times do you have to pick a number at random in order that your chance
> of success becomes 50% at least?

It is a well known fact that if 23 people are picked at random (whatever
that may mean) then the probability that at least two will have the same
birthday (disregarding year) is a little more than 50%. Is that
relevant? 'Cuz if it is, you should look up 'birthday paradox'.

--
When a true genius appears in the world, you may know him by
this sign, that the dunces are all in confederacy against him.
Jonathan Swift: Thoughts on Various Subjects, Moral and Diverting

Date Subject Author
3/11/12 Jose Carlos Santos
3/11/12 Frederick Williams
3/11/12 bert
3/11/12 Jose Carlos Santos
3/11/12 quasi
3/11/12 quasi
3/11/12 Jose Carlos Santos
3/13/12 Ray Koopman
3/12/12 Tim Little