RE: math question verrrrrry off topic
Huh!!!? After all this time, I thought I finally got it right, but it looks like what I got is the flipped/wrong version! Since this is off topic, I won't ask further. I will have to read some stats book again. Good that I don't go to casino! Whew! :-) Dave > -----Original Message----- > From: Katharine Thayer [mailto:kthayer@pacifier.com] > Sent: Saturday, January 19, 2008 11:14 AM > To: alt-photo-process-l@usask.ca > Subject: Re: math question verrrrrry off topic > > This is (one reason) why casinos make so much money, because > people make the mistake of thinking the probability of the > next throw depends somehow on how the die has fallen on the > last throw, but it > doesn't. No matter how many times you throw the die, and no matter > how the die has fallen before, the probability of a 1 on the > next throw is still 1/6. > > > > On Jan 19, 2008, at 7:57 AM, Dave S wrote: > > > I must say that even in simple probability, the concept is a little > > hard to grasp for me. I can do the math, but to FEEL it is > different. > > > > Say I am throwing a dice now. The chance of getting a 1 is 1/6. > > Let's say I > > did get a 1. Now I am throwing again. I pick up the same > dice and make > > the same random throw. On one hand I think everything is > the same, so > > the probability of getting 1 should still be 1/6. On the > other hand, > > of course, chances of getting two 1's in a row is lesser, so the > > probability is now 1/36. > > > > If this is an exam in the statistics class, I can do the math and > > pass, but up to this day, my mind would still flip one way > or another > > because both are making some sense to me. Isn't this weird? > > > > > > Dave > > > > > >> -----Original Message----- > >> From: Katharine Thayer [mailto:kthayer@pacifier.com] > >> Sent: Saturday, January 19, 2008 9:52 AM > >> To: alt-photo-process-l@usask.ca > >> Subject: Re: math question verrrrrry off topic > >> > >> Okay, look. > >> > >> If this were a simple probability experiment, let's say there were > >> 600 objects in a big jar, all exactly the same size and shape and > >> differing only in color: 450 red ones (for > >> not-accepted) and 150 green ones (for "accepted") all mixed up > >> really well, and the question was, "if some people from College X > >> reached into the jar blindfolded and three of them pulled > out green > >> objects, what would the probability of that result be, would it be > >> 1/4x1/4x1/4?" then the answer would be "only if just > three people > >> from College X reached into the jar. If more than three > people from > >> college x reached into the jar, let's say five people from > college x > >> reached into the jar, then the probability of three of those five > >> people pulling out a green marble would be 1/4 x 1/4 x 1/4 x > >> 3/4 x 3/4." > >> > >> But of course this isn't anything like that. In this > case, the 600 > >> objects in the jar are made by the people who are being > selected, and > >> the objects are all different, all different sizes and shapes and > >> colors, and made of different materials. People might contribute > >> different numbers of objects (though it's never been clear to me > >> whether that's the case or not) in which case the objects > made by the > >> same person presumably aren't as different from each other as the > >> objects made by different people. And the selection is > made not by > >> the people themselves reaching into the jar blindfolded, but by a > >> third party, a judge, who also doesn't reach into the jar > blindfolded > >> and pull out objects randomly to make a selection, but > pours them all > >> out on in a big tray and looks at all 600 of them closely before > >> deciding which ones he/she wants to include. This > particular judge > >> might be drawn to metal objects, or even especially to > platinum over > >> silver, or maybe he or she particularly dislikes street scenes and > >> prefers pictures of old mills, or is looking for a certain > level of > >> craftsmanship in the work, or maybe the criterion is > something even > >> more difficult to articulate, whether the judge "likes" > something or > >> not. > >> Whatever the criteria, by the end of the day, the objects are > >> separated into two piles, "accepted" and "not accepted," and there > >> are 150 objects in the first pile and 450 in the second pile. > >> > >> I hope it should be clear to everyone at this point how different > >> this is from the problem above, and why you can't treat this as a > >> problem of simple probability and say that the probability of any > >> entry being accepted is the same as the probability of any other > >> entry being accepted, and that this equal probability for > each entry > >> is 1/4, since 1/4 of all the entries were accepted. It's just not > >> that kind of problem, and it doesn't work to treat it that way. > >> Thank you. > >> Katharine > >> > >> > >> > >> > >> On Jan 18, 2008, at 6:49 PM, Katharine Thayer wrote: > >> > >> > >>> :--) > >>> > >>> > >>> On Jan 18, 2008, at 6:23 PM, Diana Bloomfield wrote: > >>> > >>> > >>> > >>>> Hey Katharine, > >>>> > >>>> I don't know-- maybe. I honestly didn't read the other > >>>> > >> answers. :) > >> > >>>> > >>>> > >>>> On Jan 18, 2008, at 8:43 PM, Katharine Thayer wrote: > >>>> > >>>> > >>>> > >>>> > >>>>> Hmm, I thought that's what we all already have said, isn't it? > >>>>> That that theoretical probability (1/4x1/4x1/4) would > >>>>> > >> hold only if > >> > >>>>> assumptions were met, and since assumptions are > >>>>> > >> obviously not met > >> > >>>>> (for example, judging is not a random lottery of course > >>>>> > >> but is done > >> > >>>>> on the basis of criteria, arbitrary or otherwise but > >>>>> > >> certainly not > >> > >>>>> random). Also, no one has said whether the 600 entries are 600 > >>>>> works or 600 people; I was assuming that they are 600 works > >>>>> representing fewer than 600 people, in other words people could > >>>>> submit more than one work, in which case, as I said, the > >>>>> > >> number of > >> > >>>>> works submitted per person would also have to be > figured into the > >>>>> equation somehow. Besides, if one person submits ten > pieces and > >>>>> another person submits one, the ten pieces by the one person > >>>>> couldn't be considered independent entries in the same > way one of > >>>>> those ten could be considered independent of the one from > >>>>> > >> the other > >> > >>>>> person, and independence is also an assumption that must > >>>>> > >> be met in > >> > >>>>> order to consider the probability of acceptance to be the > >>>>> > >> same for > >> > >>>>> all entries. > >>>>> Katharine > >>>>> > >>>>> > >>>>> > >>>>> > >>>>> On Jan 18, 2008, at 4:25 PM, Diana Bloomfield wrote: > >>>>> > >>>>> > >>>>> > >>>>> > >>>>>> Okay, Chris. Here is it-- straight from my resident > >>>>>> > >> statistician > >> > >>>>>> here: > >>>>>> > >>>>>> If they were the only 3 people from that institution who > >>>>>> > >> applied, > >> > >>>>>> AND if judging was completely random, then the > >>>>>> > >> probability of this > >> > >>>>>> is roughly 1 in 64 (key word: roughly). If more than > >>>>>> > >> that applied > >> > >>>>>> from this same institution, and only 3 got in, then the > >>>>>> > >> calculation > >> > >>>>>> will be more complex. > >>>>>> > >>>>>> Hope that helps. :) > >>>>>> On Jan 17, 2008, at 12:00 PM, Christina Z. Anderson wrote: > >>>>>> > >>>>>> > >>>>>> > >>>>>> > >>>>>> > >>>>>>> Where else but this list can I ask these weird > questions about > >>>>>>> chemistry and math and computers and alt??? > >>>>>>> > >>>>>>> OK for you math people (Yves?): If there is a show and 600 > >>>>>>> entries, and 150 are accepted, there is a 1 in 4 chance of > >>>>>>> acceptance. If 3 people from the same institution > are accepted > >>>>>>> what percent chance is that--is it 1/4 x 1/4 x 1/4 or a 1.5% > >>>>>>> chance or is it a more complex formula? > >>>>>>> > >>>>>>> Forgive the off topic request but it does relate to > >>>>>>> > >> photo as 3 of > >> > >>>>>>> our program got into a photo show and I want to be able to > >>>>>>> mathematically brag about it to the dept. head/dean. > >>>>>>> Chris > >>>>>>> > >>>>>>> Christina Z. Anderson > >>>>>>> Assistant Professor > >>>>>>> Photo Option Coordinator > >>>>>>> Montana State University > >>>>>>> CZAphotography.com > >>>>>>> _______________ > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>> > >>>>>> > >>>>>> > >>>>>> > >>>>>> > >>>>> > >>>>> > >>>>> > >>>>> > >>>> > >>>> > >>>> > >>>> > >>> > >>> > >>> > >> > >> > >> > >> > > > > > > > > >
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