Date: Mon, 26 Apr 1999 15:54:07 -0700
Message-Id: <v01510100b34a26ea5522@[156.1.188.13]>
To: "Pinhole Listserv" <pinhole@exploratorium.edu>
From: rdelwic@muse.sfusd.k12.ca.us (Richard Delwiche)
Subject: Re: Pinhole Digest #168 - 04/24/99
Okay,
I have to weigh in on this one. Being one of the younger in a series of
sons, I can attest that there is a definite possibility parents with two
(or more) same-sex children will decide to try for one of the other sex.
Therefore my guess is that a slightly higher proportion of two-child
families are one boy / one girl, than the 50% dictated by pure chance if
family size was independant of offspring gender.
To state the same argument differently, parents whose first two children
are both boys or both girls are more likely to have a third child than
those whose have a boy and a girl, thus disqualifying their children from
saying "I have only one sibling" as posed in the question.
Am I making sense?
Richard
>----------------------------------------------------------------------
>
>Subject: probability
>From: Ian Bleakney <bleekers@ousd.k12.ca.us>
>Date: Thu, 22 Apr 1999 05:48:11 -0600
>
>Hey pinholers, a probability question:
>
>Let's pretend that you meet a person and she says that she has only
>one sibling. What is the probability that her sibling is a boy? How
>about a girl? I'm pretty sure that it is not 50:50....
>
>(So, in real life, if you meet a woman with one sibling, is there
>really a better chance of her having a brother than a sister?)
>
>Stumped in Oakland
The enchantments of life lie solely in the great friendships we form.
- al Muhalhil
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
rdelwic@sfusd.edu Richard C. Delwiche
Phone: 415.749.3476
Math - Science - Art - Language
FAX: 415.563.8965
Learning Disabilities Specialist
Ben Franklin Middle School
1430 Scott St.
San Francisco CA94110