perplexus.info :: Just Math : The odds stay unchanged

The odds stay unchanged (Posted on 2004-06-17)

On a certain island each of the inhabitants is a member of one of the two existing clubs.

The membership distribution is such that when two random people meet, the probability of those two belonging to the same club is equal to the probability of them belonging to distinct clubs.

When 100 newcomers arrive on the island and each enrolls in one of the two clubs, the distribution still retains this feature. How many people belong to either club?

See The Solution Submitted by Ady TZIDON

Rating: 4.2727 (11 votes)

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Subject	Author	Date
Puzzle Solution	K Sengupta	2008-05-27 15:50:58
Answer	K Sengupta	2008-05-23 06:14:12
full solution	Bon	2004-07-12 17:24:56
che??	vije	2004-07-07 13:22:37
re: generalisation ==> author's remarks	Ady TZIDON	2004-06-20 11:00:07
More about generalization:	Gamer	2004-06-19 18:27:45
Another Approach	Gamer	2004-06-18 23:22:00
re(2): ution - NON trivial solution	Ady TZIDON	2004-06-17 18:23:25
re: Non-trivial answer by brute force	Dan Blume	2004-06-17 16:28:30
re: Non-trivial answer by brute force - sorry, no	Thalamus	2004-06-17 16:25:12
Non-trivial answer by brute force	Dan Blume	2004-06-17 16:18:08
re(2): A trivial solution - NON trivial solution	SilverKnight	2004-06-17 15:51:30
re: A trivial solution - NON trivial solution	Erik O.	2004-06-17 15:41:35
A trivial solution	Erik O.	2004-06-17 15:13:39
hints - partial solution	Erik O.	2004-06-17 14:41:36
re(2): First meeting (hint)	Dan Blume	2004-06-17 14:00:50
re: Possibility? (spoiler?)	Charlie	2004-06-17 13:57:38
re: Possibility? (spoiler?)	SilverKnight	2004-06-17 13:57:26
Possibility? (spoiler?)	Richard	2004-06-17 13:54:38
re: First meeting (hint)	Thalamus	2004-06-17 13:54:02
First meeting	Dan Blume	2004-06-17 13:45:24

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