"William B. Ware" wrote:
>
> Interesting question... It seems to me that, if the correct answer is 8,
> then the "questioner" was asking about permutations, taking birth order
> into account. If the question is about "combinations," then I see the
> possibilities as:
>
> 3 boys
> 2 boys, 1 girl
> 1 boy, 2 girls
> 3 girls...
>
> So I would propose "4" as the answer...
There is usually (always?) more than one way to set up a sampling space
for a given problem. Thus, the problem is one of judgement... A few
heuristics I've found useful:
In setting up a sampling space, much trouble is avoided by using
equiprobable events, if possible. The four above aren't.
It is also usually good practice to use as fine-grained a sampling
space as could possibly be relevant to the question; events in the
sampling space are generally treated as atomic. Again, this suggests
the answer "8".
And, finally, it is a mistake to try to build too much structure into
the sampling space. Keep it simple and do the math elsewhere.
-Robert Dawson
.
.
=================================================================
Instructions for joining and leaving this list, remarks about the
problem of INAPPROPRIATE MESSAGES, and archives are available at:
. http://jse.stat.ncsu.edu/ .
=================================================================
