Population control (Posted on 2002-05-05)

	Submitted by levik
Rating: 3.5714 (7 votes)
Solution:	(Hide)
Assume the country has N families. Since every family will have children until a daughter is born, they will have N daughters. But there is a 1/2 chance that the first child will be a boy, making for N/2 "firstborn" boys. There is also a 1/4 chance that the second child will be a boy as well, for a total of N/2 + N/4 boys among the first- and second-born. It is easy to see that after each child, the chance that all the children are boys is reduced by 1/2, so the total number of boys is equal to N/2 + N/4 + N/8 + ..., an infinite series that adds up to N. So the ratio of boys/girls in the country will actually be 1 to 1, unaffected by the strange custom.

	Subject	Author	Date
	answer	K Sengupta	2007-04-15 13:53:44
	The word "equal" and more rants	Mike	2005-05-09 23:29:54
	re: Simple solution	ajosin	2005-03-04 01:29:01
	umm	Vito	2003-09-06 16:12:04
	Simple solution	Federico Kereki	2003-07-27 05:11:05
	Rrg Hard	Matthew Bobbins	2003-02-27 10:19:57
	re(3): Wasn't it obvious?	levik	2002-07-09 04:30:34
	re(2): Wasn't it obvious?	TomM	2002-07-08 22:01:20
	re: Wasn't it obvious?	levik	2002-07-08 08:20:58
	haha nice	qball	2002-07-06 23:05:47
	Wasn't it obvious?	TomM	2002-05-10 22:55:50
	thats the same answer	theBal	2002-05-07 07:52:44
	solution..I think	btrnviagra	2002-05-07 00:55:15
	one half	theBal	2002-05-06 17:42:41