Re: Tuesday birthday problem
- --- In RangeVoting@yahoogroups.com, "Andrew" <range001mmsny@...> wrote:
>--oops... ok, I was going to apologize for my counting error & Markus Schulze & S.Unger
> These calculations are right, and Stephen and Markus are right, too. 6/13 is the right answer.
> If you're comparing your answer to the one at http://sciencenews.org/view/generic/id/60598/title/When_intuition_and_math_probably_look_wrong
> then you need to realize that you've changed the problem by adding the word "exactly". The riddle as stated there allows both children to be boys born on Tuesday. In that case, the answer is 13/27.
had it right since they avoided my 27 vs 28 count-error..., but... it may be the science news thing made the same error I did, or it may be they had a different problem
in mind (depends on how you interpret the words, shows the importance of precise wording). I don't know. Anyhow, we all understand the truth now, so I quit.
- --- In RangeVoting@yahoogroups.com, "brokenladdercalendar" <thebrokenladder@...> wrote:
>--for this reason one should say "exactly one" or "at least one" or "at most one"
> --- In RangeVoting@yahoogroups.com, "Andrew" <range001mmsny@> wrote:
> > If you're comparing your answer to the one at http://sciencenews.org/view/generic/id/60598/title/When_intuition_and_math_probably_look_wrong
> > then you need to realize that you've changed the problem by adding the word "exactly". The riddle as stated there allows both children to be boys born on Tuesday. In that case, the answer is 13/27.
> The riddle says "one of whom is a boy born on Tuesday". In normal English, that means exactly one, otherwise they'd have said "at least one of whom". For instance, if someone says, "I have two dogs", it could be that he has exactly four dogs, but a reasonable person would take that to mean "exactly two dogs".
> Clearly you are right about their intent, but I say they mis-stated the problem.
and not just "one" because the latter is ambiguous. Relying on notions of "normal english usage" is asking for damage. A lot of huge errors stem from trivial communication
issues like that. That's how the USA lost two costly Mars probes, for example, sending
over $100 million and many entire careers down the toilet. It's appalling how often I see crap in the media like "the temperature was 30 degrees." What the hell does that mean? Whenever engineers communicate in that fashion, the result is likely to be a lost Mars probe. I daresay the USA is losing a tremendous albeit unquantifiable amount because of its refusal to switch to the metric system (unlike every other country in the world) thus automatically avoiding such errors. This is not only lost money but also lost lives. It is absolutely astounding the lengths to which people go to avoid using the metric system, for example measuring vitamin doses in magic invented "vitamin units" rather than the obvious (grams). Can you imagine how many people must die every year because of such
pointlessness leading to medical errors?
The simple act of counting is amazingly hard for humans, evidently including me, and another frequent source of errors. As the saying goes, "there are three kinds of mathematicians, those who can count, and those who can't"...
Finally, probability problems of this ilk are a notoriously error-prone basically because
people think they intuitively know the answer immediately without calculating, hence do not do the calculation.
So... three big sources of errors in the world.