Ask MetaFilter questions tagged with math
http://ask.metafilter.com/tags/math
Questions tagged with 'math' at Ask MetaFilter.Thu, 17 Apr 2014 10:21:23 -0800Thu, 17 Apr 2014 10:21:23 -0800en-ushttp://blogs.law.harvard.edu/tech/rss60Why is the center of a circle often given as (h, k)?
http://ask.metafilter.com/260472/Why%2Dis%2Dthe%2Dcenter%2Dof%2Da%2Dcircle%2Doften%2Dgiven%2Das%2Dh%2Dk
Why are the letters 'h' and 'k' often used to represent the center of a circle in the standard equation of a circle:
(x - h)<sup>2</sup> + (y - k)<sup>2</sup> = r<sup>2</sup>
are 'h' and 'k' short for something? I might guess 'h' is short for 'horizontal', but I can't imagine what 'k' is for. So why do we use (h, k) rather than (a, b) or some other pair of letters? My Googleing shows I'm not the first person to wonder this, but no one seems to have received a good answer.tag:ask.metafilter.com,2014:site.260472Thu, 17 Apr 2014 10:21:23 -0800Reverend JohnWhat's a good topic for a one-hour math lecture?
http://ask.metafilter.com/260101/Whats%2Da%2Dgood%2Dtopic%2Dfor%2Da%2Done%2Dhour%2Dmath%2Dlecture
I work as a math tutor at a community college and have the opportunity to spend an hour teaching math to a group of students preparing for a the college's math placement test. Now, I don't know what's on the placement test, but I want to teach something that's more engaging and conceptually accessible than "here's how to multiply (4x+3)(2x+5)", since I can't possibly review all of high-school math in an hour and don't think the students will get much from just another lecture. What are some interesting topics that I can explore that will be accessible and memorable?tag:ask.metafilter.com,2014:site.260101Thu, 10 Apr 2014 10:24:33 -0800LSKArticle about Common Core math
http://ask.metafilter.com/259860/Article%2Dabout%2DCommon%2DCore%2Dmath
Trying to find an article I read sometime in the last three months about Common Core math. The article started out talking about why Common Core math does make sense. It then described how basic addition and subtraction seem simple but are actually quite difficult concepts at a young age, in addition to being boring. In contrast, the basic concepts of knot theory and set theory are more interesting and more accessible at a young age. The researcher in the article (possibly the author) wanted to find more concepts that are interesting and accessible - I think there was a phrase about finding "advanced but conceptually simple" topics - to make math more appealing intuitive for kids. <br>
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I think I read this in the New York Times, but I'm not sure.tag:ask.metafilter.com,2014:site.259860Sat, 05 Apr 2014 19:56:31 -0800Questolicious[MathFilter] Taking for-credit math classes online
http://ask.metafilter.com/259817/MathFilter%2DTaking%2Dfor%2Dcredit%2Dmath%2Dclasses%2Donline
For professional and academic reasons, I need to take a number of college-level math classes (mainly Calculus and Linear Algebra) in a relatively short period of time (4-6 months). They need to be online, for-credit, and I need to be able to do them at my own pace, meaning faster than a normal 1-course-per-semester flow. I've already found <a href="https://netmath.illinois.edu/">https://netmath.illinois.edu/</a>, but the classes are terribly expensive, so I'd like to learn of other alternatives that don't cost as much.tag:ask.metafilter.com,2014:site.259817Fri, 04 Apr 2014 18:35:53 -0800dcrochaVon Neumann I am not
http://ask.metafilter.com/259473/Von%2DNeumann%2DI%2Dam%2Dnot
I’ve spent my 20s building a BS “identity” as an “analytical type of person". Help me grow up. Snowflakes inside. I should be graduating in the next few months with an economics PhD. When I finished high school I didn’t go to university directly. I worked and during that time decided I wanted to study it at undergraduate level. (Understanding things about the world which seemed powerful and mysterious was originally the attraction). Economics has lot of math. Previously I had been very poor at math. I’m in a European country where one can choose to not study math in last two years of high-school, and I didn’t. I enrolled in one of the few university courses in my country which at the time accepted economics students without having studied math for the last two years of high-school. As an undergraduate at university I studied relentlessly (and also brought my math up to speed –in fact further than what was necessary as I wanted to do graduate level econ study - in my spare time calculus, linear algebra, statistics, probability, a little bit real analysis) and did very well as far as that course went. <br>
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Then I did an MSc in econometrics (no GRE or entrance tests there). During that year I got a chronic fatigue illness and struggled to complete my MSc thesis. Then I applied to a grad school which enabled me to again avoid GREs and entrance tests. <br>
Grad school was a disaster. I hated the grad school courses. I realised I also have a problem following presentations and that I am slow at reading papers. Imposter syndrome set in. My chronic fatigue continued (I should have taken time off but didn’t). I found that I had been focussing on analytical deduction at the expense of evidence, (and I was weak in dealing with latter.) I also found the various expected standards inconsistent and therefore confusing. When I look back, the only things I enjoyed in four years were writing scripts in statistical software packages for data collection, processing and analysis (the problem was self contained, the only criterion for success was “does it work?”, there was no-one to compare my performance too). I almost quit, but finally submitted, and passed. I dislike my thesis, don’t trust the results and do not want to publish them, despite the reassurances of my supervisors. I don’t think that I have a future in academia.<br>
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All the while I’ve been aware that although I’ve learned a lot of math compared to what I used to know, I’m still not any good with numbers. Probably a little less hopeless than before. But it takes me ages to work out anything in my head, and I just can’t do it under pressure. I just failed to get through a basic math test for a government job, which involved no above high-school math at all. I realised that all I can do is (not advanced) “math with letters” and next to no “number sense”. I’m also aware that my understanding of how the economy really works, despite all this study, is probably worse than someone who didn’t do any of it. <br>
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But more importantly, I’m pretty sure that I have spent most of my 20s trying to create an idea of myself of some “analytical type person” which I never was (and attempting to avoid disturbing but potentially useful evidence to the contrary). I believe that I’m an anxious and insecure person and somehow I think it served as a shortcut to an adult identity. But now I’m aware that it’s nonsense (and actually harmful to becoming a mature adult), but at the same time not able to detach myself from the most unhelpful thoughts – sometimes feeling stupid and worthless, and more generally having a fragile ego. <br>
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How can I move forward? I’d like advice on detaching my sense of self-worth from this “analytical type of person” idea that I’ve built up over the years. Very soon I'm going to need a job, and I’d like to find a job in which I feel good enough. Have any of you stuck with a field or some broadly defined area, despite a feeling of large intellectual limitation, dealt with those feelings and made it work?tag:ask.metafilter.com,2014:site.259473Sat, 29 Mar 2014 18:24:35 -0800AnonymousCalculus after being away from algebra for some time. Help me.
http://ask.metafilter.com/259184/Calculus%2Dafter%2Dbeing%2Daway%2Dfrom%2Dalgebra%2Dfor%2Dsome%2Dtime%2DHelp%2Dme
I am going to grad school in the fall. Hooray! Problem: I have to take calculus before I start and I am kind of freaking out. Everything is great about the grad program I've decided to attend. The only problem is that I found out with my admission that they want me to have calculus before I start. I haven't had calculus. It was news to me that I needed to do it before starting (non-math intensive field), but attending a different program that doesn't require it is not really a good option at this point, as this program is far and away the best financial option I have.<br>
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They said I can take any sort of calculus I want and that it can be at a university, community college, or online. I have opted to take a course called "Calculus for Business, Management, Social and Life Science" at my local community college. It starts in one week. <br>
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I had trig and pre-calc in high school, but other than that I have been away from higher level algebra for kind of a long time. I took stats recently with no problems and I also took Trig-Based General Physics last fall without too many problems. I also took the GRE last summer which required me to basically re-learn high school level algebra and geometry and did well. <br>
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I am more or less good at math, but I am really, really worried about my algebra not being up to snuff and failing miserably. I feel more or less comfortable working with basic trig, quadratic equations, basic algebraic operations. I have to go/no-go to all my grad programs by April 15th, so I'm concerned that I will accept the offer, turn down the others, and then fail calculus and totally screw myself.<br>
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I spoke with the professor about my situation. He scared me with how difficult this was going to be. He also said there are some others in the class in a similar situation to mine. I also have people close to me who are engineers/math students who I can enlist to help me a bit. I don't need to excel in the course, but I do need to pass.<br>
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-How screwed am I?<br>
-Are there any strategies that can help me best succeed in this situation? Resources? Things I'm not thinking of?<br>
-I am willing to dedicate as much time as it takes really to make this work. What should I be preparing for/reviewing?<br>
-Any other advice?<br>
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Thanks everyone.tag:ask.metafilter.com,2014:site.259184Mon, 24 Mar 2014 11:51:35 -0800The Pantless WonderChance of event with small sample size, based on larger related sample?
http://ask.metafilter.com/258957/Chance%2Dof%2Devent%2Dwith%2Dsmall%2Dsample%2Dsize%2Dbased%2Don%2Dlarger%2Drelated%2Dsample
Can/how can one improve the estimate for a chance of an event with a small historical sample size by utilizing the chance of a related event with a large historical sample size? Example and half-assed guess inside. A baseball-related example (for the purposes of this question, please forget about complicating factors like lefty/righty splits, home/away splits, the fact that a particular player might be better or worse now than he was in the past, etc.):<br>
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Joe has had 1000 at bats. He has gotten a hit in 270 of those 1000 at bats.<br>
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Of those 1000 at bats, 10 were against the pitcher Fred. In those 10 at bats against Fred, Joe got six hits.<br>
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Clearly we can say "Joe is a .600 hitter against Fred". But also clearly, that doesn't really have any meaningful predictive power for Joe's future at bats against Fred. If we want to guess what the chance of Joe getting a hit off of Fred is, 27% is almost certainly a much better guess than 60%.<br>
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But can we use <i>both</i> pieces of information to get a guess that's better than "27%"?<br>
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I have a half-assed guess, which I'll describe momentarily, but it occurs to me that this is probably a problem which has been thought about rigorously by mathematicians. So does anyone know if there's a "real" answer to this problem?<br>
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My half-assed guess is something along these lines:<br>
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Joe has 10 at bats against Fred, and 6 hits in them. But Joe has 1000 at bats total (with 270 hits). Let's assume that if Joe had had 1000 at bats against Fred, 10 of them would have gone as they did, and the other 990 would have been as if against an average pitcher. So Joe would have gotten:<br>
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6 + 990 * 270 / 1000<br>
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= 6 + 267.3<br>
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= 273.3<br>
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So we guess that in his upcoming at bat against Fred, Joe has a 27.33% chance of getting a hit.tag:ask.metafilter.com,2014:site.258957Thu, 20 Mar 2014 07:20:36 -0800FlunkieYou Can't Handle the (Next) Proof!
http://ask.metafilter.com/258894/You%2DCant%2DHandle%2Dthe%2DNext%2DProof
Working through Apostol's Calculus Volume I for personal development. Stuck on a proof, again. Can you help? Apologies for the ugly formula approximation. Difficulty: prove by induction.<br>
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(1 + 1/n)^n = 1 + Σ (k= 1 to n) {1/k! π (r = 0 to k-1) (1 - r/n) }<br>
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Yes, that's product notation after the 1/k! term. Any help appreciated, as I'm not seeing this one after leaving it uncompleted and circling back for a couple weeks.tag:ask.metafilter.com,2014:site.258894Tue, 18 Mar 2014 17:23:27 -0800bfranklinHow to take scientific notes efficiently?
http://ask.metafilter.com/258847/How%2Dto%2Dtake%2Dscientific%2Dnotes%2Defficiently
What is the best way to take grad level notes that feature tons of text, math equations and diagrams, during class, while reading books, and while reading research?
Ability to search and organize a huge plus!
Digital or non-digital solutions considered. So I’ve been working for the past 10 years but am going back to grad school next fall for a PhD – starting to read up but realized I needed to take notes again, which I’ve pretty much forgotten how to do.<br>
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I used to do loose paper + binder, but I’m sure new things have come up since then. Is the iPad + stylus really an option? Not sure I would be able to type fast enough on it though? How does it work for equations? Is some kind of Mac laptop a better option? Which one? Should I get a drawing pad to add to the Mac? Etc…..<br>
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Thanks!!!tag:ask.metafilter.com,2014:site.258847Tue, 18 Mar 2014 05:10:33 -0800RitonIn Need an Nerdy T-Shirt for Tomorrow (3.141592654...)
http://ask.metafilter.com/258624/In%2DNeed%2Dan%2DNerdy%2DT%2DShirt%2Dfor%2DTomorrow%2D3141592654
Okay, I'm in NYC and I need a PI related T-Shirt for<a href="http://en.wikipedia.org/wiki/Pi_Day"> Pi-Day</a>tomorrow... Anyone know of any stores where I can get one? (It's too late for an online order)tag:ask.metafilter.com,2014:site.258624Thu, 13 Mar 2014 07:08:44 -0800Stu-PendousWhy do we have order of operations in arithmetic?
http://ask.metafilter.com/258530/Why%2Ddo%2Dwe%2Dhave%2Dorder%2Dof%2Doperations%2Din%2Darithmetic
Why do we have order of operations rules in arithmetic instead of just strictly evaluating expressions from left to right (possibly with parenthesis for grouping if we really wanted to change the order)?tag:ask.metafilter.com,2014:site.258530Tue, 11 Mar 2014 11:49:07 -0800Reverend JohnIs this science or a sort of engineering? How do I learn more about it?
http://ask.metafilter.com/258160/Is%2Dthis%2Dscience%2Dor%2Da%2Dsort%2Dof%2Dengineering%2DHow%2Ddo%2DI%2Dlearn%2Dmore%2Dabout%2Dit
My ignorance of science and engineering concepts, procedures, and methods of calculation is holding me back from tackling a whole mess of fun stuff. But what fields am I even interested in, and how can I learn more? Where do I begin? I love problem solving and am good with my hands, so I have all kinds of odd technical projects going all the time. Some examples of what I've been playing with over the past few months: DIY filtration methods for my freshwater planted and reef tanks, DIY automated water change and water conditioning for those tanks, DIY live food cultivation and automated feeding methods for those tanks, fixing up a second-hand bicycle and modding it out as a moped, etc. I'd like to learn more about things like water filtration, how engines work, robotics, gardening -- just a whole mess of stuff. <br>
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The problem is, I was a creative writing/English major in undergrad and am studying social sciences in grad school now (I'm 28); the last time I took a "hard" math or science was in 12th grade. Growing up, I was a good student and didn't struggle in math or science, but it just never occurred to me to do anything in those subjects. Now I don't have the tools to learn much more about them on my own, but I need to learn a lot more about them to keep going in my hobbies. Plus, this stuff is fun!<br>
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So how can I learn more, both in terms of (hands-on) projects and classes? What fields would these sorts of interests fall under, anyway? What kinds of skills or knowledge should I develop?<br>
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The only caveats I want to put on suggestions are: I love getting my hands dirty and hate following directions. So computers and programming aren't really my bag, but living creatures (plants, animals, viruses, bacteria, etc etc etc) and other things that move (like water and air) definitely are.tag:ask.metafilter.com,2014:site.258160Tue, 04 Mar 2014 13:06:42 -0800rue72Well-written math
http://ask.metafilter.com/257907/Well%2Dwritten%2Dmath
Which mathematicians write exceptionally well or exceptionally clearly? (Individual books or articles would also be acceptable.) As I contemplate assembling the bits of my dissertation, I realise that my writing leaves something to be desired. It's like if Kafka wrote math with no exposition between propositions. Kafka's great and all, but that many clauses doesn't go so well for me. But I find myself not knowing who to look to for clear exposition. I've heard Atiyah's name mentioned for this once or twice, but who else? Or are there exceptionally well-written books or articles I could look at?<br>
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Note: Simon Singh is not an answer to this question. 'Popular math' is not what I'm looking for.tag:ask.metafilter.com,2014:site.257907Fri, 28 Feb 2014 07:03:56 -0800hoylandWhere can I take an online linear algebra course this summer?
http://ask.metafilter.com/257616/Where%2Dcan%2DI%2Dtake%2Dan%2Donline%2Dlinear%2Dalgebra%2Dcourse%2Dthis%2Dsummer
I have $800 for tuition reimbursement, and would like to take a linear algebra online course this summer. It doesn't matter if its for credit or not. Thanks!tag:ask.metafilter.com,2014:site.257616Sun, 23 Feb 2014 08:48:26 -0800MisantropicPainforestRegarding the M in STEM
http://ask.metafilter.com/256900/Regarding%2Dthe%2DM%2Din%2DSTEM
What are some of the newest methods being used these days to teach young children arithmetic? I've heard there are some newer pencil-and-paper methods in particular for teaching multiplication and division. I would like to know more about these methods (what they are called, what exactly they are, what are the benefits, etc.). Where can I find information about the latest and greatest ways to teach math to young schoolchildren? I'm aware of Singapore Math and Saxon and other programs - my question is more about specific methods for teaching arithmetic, in particular multiplication and division.tag:ask.metafilter.com,2014:site.256900Mon, 10 Feb 2014 12:08:17 -0800DansamanWas Fifth Grade math always this hard?
http://ask.metafilter.com/256099/Was%2DFifth%2DGrade%2Dmath%2Dalways%2Dthis%2Dhard
Can you show us how to solve a math word problem? My granddaughter was given this question as a "Stretch Your Thinking" section of a fifth grade math assignment. She's turning the homework in without an answer, so we're not "cheating". <br>
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However, neither she nor her parents nor I could come up with a solution process. I told them MetaFilter ALWAYS has an answer. Please......!<br>
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Here's the question:<br>
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"I am a number less than 3,000. When you divide me by 32, my remainder is 30. When you divide me by 58, my remainder is 44. What number am I?"<br>
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Please show your work.tag:ask.metafilter.com,2014:site.256099Tue, 28 Jan 2014 07:36:50 -0800uncakenSingapore Math
http://ask.metafilter.com/256083/Singapore%2DMath
I'm trying to help my 3rd grader with his math homework, but we are stuck on one problem. I can solve it using Algebra, but I'm trying to figure out how to explain it to him using the <a href="http://files.eric.ed.gov/fulltext/EJ848499.pdf">Singapore method</a> that he's taught in school. Note that he hasn't learned how to add negative numbers, which puts a crimp on the methodology. Problem: In 2 years, Tom will be twice as old as he was 5 year ago. How old is Tom now?<br>
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My solution: x+2=2(x-5). If you solve for x, the answer is 12<br>
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The Singapore solution? This is where I am stuck. I don't understand how to use the bar ("strip diagram") method to model the problem in a way that a 3rd grader taught the Singapore method can solve.tag:ask.metafilter.com,2014:site.256083Mon, 27 Jan 2014 21:23:52 -0800agogYou Can't Handle the Proof!
http://ask.metafilter.com/255946/You%2DCant%2DHandle%2Dthe%2DProof
Working through Apostol's Calculus Volume I for personal development. Stuck on a proof. Can you help? Trying to prove that 2(sqrt(n+1) - sqrt(n)) < 1/sqrt(n) < 2(sqrt(n) - sqrt(n-1)), n >= 1. I can make a damn fine geometric argument for this, but I can't seem to analytically prove it from the field, order, and least-upper bound axioms. Hope me!tag:ask.metafilter.com,2014:site.255946Sat, 25 Jan 2014 14:35:16 -0800bfranklinTable top brainteaser puzzles
http://ask.metafilter.com/255507/Table%2Dtop%2Dbrainteaser%2Dpuzzles
Where can I find more good ideas for brainteaser puzzles like <a href="http://www.flickr.com/photos/bleyleluehrs/sets/72157606501935844/">these</a>? A friend is putting together a game/puzzle exhibit at a school science fair (ages 7 - 13) and thought a few things like this might go nicely. Ideally, these should be things which could be made from wood, played on a table top, and require some abstract thinking to solve.<br>
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Classics like the <a href="http://en.wikipedia.org/wiki/Fox,_goose_and_bag_of_beans_puzzle">fox, goose and beans puzzle</a> are great, but I probably don't know most of them. I'd like to avoid puzzles which require much special knowledge, such as chess or <a href="http://matchstickpuzzles.blogspot.com/">roman numerals</a>. Any ideas for what might go well in that setting?tag:ask.metafilter.com,2014:site.255507Fri, 17 Jan 2014 17:03:48 -0800klausmanWhy can't I differentiate this nomal/Guassian distrubution?
http://ask.metafilter.com/255470/Why%2Dcant%2DI%2Ddifferentiate%2Dthis%2Dnomal%2DGuassian%2Ddistrubution
Have a look <a href="http://s8.postimg.org/tleioykqt/image.png">here</a>. I'm assured that differentiating 1, with respect to <em>x</em>, gets you 2. Now 2 is - I think, and correct me if I'm wrong - equivalent to 3. The problem is I can't see how 3 is the result of differentiating 1. What's more, an online solver <a href="http://www.derivative-calculator.net/#expr=1%2F%282pi%2Ao%5E2%29%5E%281%2F2%29exp%28-%281%2F%282%2Ao%5E2%29%29%28%28%28x-u%29%5E2%29%29%29&simplify=1&showsteps=1">produces something (that looks) very different</a>. Can someone help me out?tag:ask.metafilter.com,2014:site.255470Fri, 17 Jan 2014 07:50:01 -0800ed\26hWhat to include in a training on maths for business people?
http://ask.metafilter.com/255311/What%2Dto%2Dinclude%2Din%2Da%2Dtraining%2Don%2Dmaths%2Dfor%2Dbusiness%2Dpeople
I've been asked at work to come up with a list of topics that could be included in a training course around basic maths for business people, and I am finding it hard to find suggestions for topics. It should all be structured around business examples and use cases, so mean, medium and mode probably make sense whereas an intro to calculus doesn't. Anything I put in is supposed to be something they can actually use, either at this stage of their career or later, but the assumption is they remain in sales/marketing and don't go on to be an analyst or anything like that. I think I may just be mentally blocked on the topic. Any thoughts from the hive much appreciated.tag:ask.metafilter.com,2014:site.255311Tue, 14 Jan 2014 15:56:07 -0800StephenFThe Gambler's Fallacy, of course. But maybe...
http://ask.metafilter.com/254967/The%2DGamblers%2DFallacy%2Dof%2Dcourse%2DBut%2Dmaybe
A coin flips three times and comes up heads 2/3. Not suspect.
But a coin flips 100,000 times and comes up heads 2 out of 3 times, that starts to look fishy. The standard probability of this is always roughly 50-50, but assuming a 2/3 ratio pointing to a "rigged" coin, how could you plot the increasing likelihood that a given coin is rigged? I've always come back to this when people discuss the Gambler's Fallacy. "The probability of <em>x</em> is ALWAYS 50/50." But how does that probability change, as the likelihood that a rigged coin is in play increases? <br>
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The Gambler's Fallacy says the probability of a pull never changes, regardless of streaks. But suppose the streak points to a hidden fact, again, over a large number of pulls. How could those streaks be used to point to a statistical anomaly, or signify that perhaps the playing field isn't as level as it could be?tag:ask.metafilter.com,2014:site.254967Wed, 08 Jan 2014 09:37:15 -0800ASozePercentage Question
http://ask.metafilter.com/254538/Percentage%2DQuestion
Help me understand percentages. Quick question about "percentages". <br>
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I know that a percentage is a number expressed as a fraction of 100.<br>
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I also know that a number can be more than 100%. For example, an item can be marked up more than 100%. <br>
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However, a lot of people also get upset when people say that you give something 110%, as it impossible to have more than 100%.<br>
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Can you help me get my head wrapped around this? In fairly basic terms?<br>
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Thanks,tag:ask.metafilter.com,2013:site.254538Tue, 31 Dec 2013 04:35:31 -0800dbirchumBad at math
http://ask.metafilter.com/254240/Bad%2Dat%2Dmath
I have a question about probability math. I am essentially flipping a coin (except instead of a 50/50 chance, my odds are 50.5% heads, 49.5% tails).
I am concerned with the probability of me hitting heads (a 50.5% chance) several times in a row. I understand the basic formula for determining the probability would be 0.505^x, where x is the number of coin flips. How do I translate this percentage chance into a number of flips I could make before I could expect to hit that result? Or the amount of time (at, say, one flip per second) that might pass before I reasonably hit a certain streak?<br>
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Say I'm wondering how long it will take me to hit a streak of 14 heads in a row, assuming one flip per second. 14 heads in a row has a 0.007% chance of occurring... so can I translate that into an amount of time (or number of flips) that might elapse before that happens?<br>
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I guess I'm confused by the idea that the probability essentially resets every time the streak is broken.<br>
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I'm pretty tired and this is pretty weird and I'm bad at math, so please feel free to call out the obvious thing I'm missing here.<br>
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Thanks!tag:ask.metafilter.com,2013:site.254240Wed, 25 Dec 2013 04:43:41 -0800disillusionedWhat is the slowest-growing whole number sequence?
http://ask.metafilter.com/253527/What%2Dis%2Dthe%2Dslowest%2Dgrowing%2Dwhole%2Dnumber%2Dsequence
What is the slowest-growing non-repeating, non-trivial* whole number sequence? * In this case, "non-trivial" means not a simple arithmetic (n, n+1, n+2, n+3...) or geometric (n×1, n×2, n×3...) sequence.<br>
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My first inclination was to go with the primes (2, 3, 5, 7, 11...). Though if we allow rounding (like a ceiling function), ceil[primes/2] might work (1, 2, 3, 4, 6...). <br>
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What do you think? An <a href="http://oeis.org/search?q=slowest+growing+non-repeating&language=english&go=Search">OEIS search</a> has not turned up anything. I'm sure someone's looked into this before, but as much as my modest research has stumped me, I'm just as interested in the thought process/derivation of the answer. There is probably a really elegant answer I'm missing!<br>
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As far as the practical application: Well... say, hypothetically, that one had a password that was required to change every so often (and not change back), and one wanted to keep things simple by just changing (in a not-easily-guessable way) a whole number appended to the end of one's password (one that won't blow up to, say... 80 digits by step #20 or so). [I will not use this method, nor should you. Probably.]tag:ask.metafilter.com,2013:site.253527Wed, 11 Dec 2013 15:00:05 -0800Eideteker