Brainteaser #34- Boys And Girls -
Imagine a village where parents continue to have children until they have a boy. If they have a girl, then
they try to have another child. If they have a boy, they stop. The probabilty of giving birth to a boy
(or girl) is 50%.
What result would this have on the proportion of boys to girls in the village?
ANSWER:
It might seem that this would lead to there being more boys than girls
but in fact the number of boys and girls would be approximately the same.
EXPLANATION: Let's say there are 40 couples in the village. When each couple has their
first child, there would be 20 baby boys and 20 baby girls. The couples who had a boy would stop having
children and the 20 couples who had a girl would have a second child. This would result in 10 new baby
boys and 10 new baby girls. The couples who had a boy would stop and the 10 couples who had a girl would
have a third child. This would result in 5 new baby boys and 5 new baby girls. Note that the number of
boys and girls remains the same throughout.
Do you have a
suggestion for this puzzle (e.g. something that should
be mentioned/clarified in the question or solution, bug, typo, etc.)?