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192 posts tagged with math *and* resolved.

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## I was told there would be no math.

I've crossed a bunch of plants with one another, and now have a bunch of berries on those plants. Each berry can contain way more seeds than I have room to pot up and grow out individually, so I'm trying to find the point of diminishing returns, where potting up additional seedlings stops giving me new and interesting results, but my math background is inadequate. [more inside]

## Excel Formula to Weight Ratings By Number of Ratings?

How do I write an Excel formula to weight a rating by the number of ratings, so that a 4 with tens of thousands of ratings weighs more than a 5 with three ratings? [more inside]

## At-Home Summer Math Program for Reluctant Teenager?

We have a 15 year old (entering 10th grade) staying with us for the summer, who needs significant help with math. He worked pretty hard this past semester to bring his math grade up to a C - and I don't want him to lose that knowledge.
What can we do to work on his math skills this summer? Open to all ideas - books, online tutorials, games.

## Remedial Maths for Grownups

What are good (and preferably free) resources for self-teaching high school level mathematics? Snowflakes etc. below the fold. [more inside]

## Counting 101 (and beyond)

Our three year old LOVES to say his letters and numbers. When he gets to Z, he triumphantly (and accurately) announces "and that's all the letters!" When he gets to 100 he proudly informs us, "that's all the numbers!" I've tried to tell him about 101, 102, etc., but he does not believe me. He would believe it if a YouTube video or app told him so. Any suggestions? (Yep, I know this is not a big deal. I just like watching the light bulb go on when he realizes just how big the world is.)

## Statistical framing of the engineering and extremism article

Reading this article on the blue got me thinking about conditional probabilities, prediction and causality. I came up with an analytical framing of what I think the article is saying and would be grateful if stats/social science Mefites could tell me if it seems accurate or else set me right. [more inside]

## Check My Math Please!

I need this for a work report, so I want to make sure I am doing this right. Could someone please verify or correct me, please?
I have two percentages and I need to figure out what percentage of change has taken place.
64.24% has changed to 74.24%
So, I think I need to do this: 74.24 - 64.24 \ 64.24 = 15.6% improvement

**or**74.24 - 64.24 \ 74.24 = 13.5% decrease## Let's play: math problems with a comm major!

I'm having trouble wrapping my head around a math equation I need to create, possibly because the data I have to cook something up with is less than ideal and only good for faking a preliminary number. Maybe you can help... [more inside]

## Looking for math and science 'jokes' to slip into a D&D adventure!

I've got the chance to run a fun, whimsical sort of D&D adventure for a friend of mine. Yay! She's a bit of a science/math geek, and very fond of The Phantom Tollbooth by Norton Juster. So I was trying to think of fun, whimsical science and math jokes and references I could slip in to a sort of 'journey with sights along the way' in the style of TPT. [more inside]

## I need some new ideas for scoring non-competitive fencing nights

I am part of a fencing club that includes a wide range of fencers, some inexperienced, some very competitive, some young teens, some over 60 and lots in between.
I have started organizing a monthly "goofball" tournament to bring out the members and to have chances to win prizes and it is going very well.
The aim, however, is not to ensure the top fencer always wins -- we have plenty of tournaments for that. What I want is to encourage maximum participation for every fencer to get on the piste and be motivated to fence a lot, and have fun. [more inside]

## Can an exact measurement ever be statistically insignificant?

I am dubious of a colleague’s assertions about statistics. [more inside]

## Godel, Escher, Bach: worth it?

Is it a waste of time for me to even attempt to read

*Godel, Escher, Bach*when I don't have a very good foundational knowledge of math? [more inside]## How to self-study science from textbooks like a boss?

I'm an (older) grad student doing research in applied physics. I've ticked all my class requirements but have a shortlist of subjects I feel would be useful to my research and my career. I've translated these into a list of reputable, recommended textbooks to read.
I've started reading those, usually in the evenings after all daily tasks are complete, and I enjoy it very much - but does anyone have tips to maximize the payoff of those reading hours? [more inside]

## Math equation problem

Asking for a friend:
I have a question about how to work out a student's exam mark.
Unit 1 is worth 60%, Unit 2 is worth 40%. Both units are marked out of 80. For example, a student scores 67/80 on unit 1 and 69/80 on unit 2. What is their overall mark?
Thanks for any help!

## Anything like the Harvard Extension School in the DC area?

I’m likely relocating to Washington DC this summer and I'm looking for somewhere where I can take Linear Algebra and a few other undergraduate math and statistics classes in Fall 2015 and Spring 2016 as a non-degree student. [more inside]

## The Mathematics Of Time

So I have a few years to kill and I'd like to spend them fully understanding what physicists and mathematicians know about time. I'm not looking for any sort of summary, I want to understand the math from the bottom up. I once caught my father going through the

*Annus Mirabilis*papers with a red pen; that's the sort of proficiency I have in mind. [more inside]## Am I doing compound interest wrong?

I'm hoping Metafilter can help me with a stupid math question, but one that's bothering me about how I was taught to compound interest versus some numbers I'm reading/hearing online about a Supreme Court case. [more inside]

## Keeping on top of the snowstorm -- does it really matter?

I am in the snowy state of Massachusetts and avoiding my next foray out to shovel. Plus, spouse and I slightly disagree on how often we really need to go out and shovel. Does it really save time to shovel every few hours throughout the storm? I have a suspicion that it doesn't really save time, and that we be just as fine waiting until the end of the snowstorm -- is there a way to think this through mathematically to find a good answer?

## I know enough calculus to think of the question but not the answer

You want to walk 10 blocks north and 10 blocks east. It would be shorter to walk along the hypotenuse, but the same distance to walk 1 block north, then 1 block east, then 1 block north, etc. it seems that if the blocks were infinitesimally short, it would approximate the hypotenuse, but alas, walking 10 blocks in one direction and then 10 blocks in the perpendicular direction is the same as dividing it up. What gives?

## How to Tell Excel to Evaluate Last Three Months (NOT Last 90 Entries)

I have an Excel spreadsheet I use to track glucose readings. There’s a value diabetics use called “A1C” which looks at the last three months of readings. It's based on a blood test, but can be estimated by averaging your readings for the last three months. I try to track every day, but I can’t reliably say “look at the last 90 values” – so I’m wondering how to set up a formula to tell it to only look at readings going back 90 days, not necessarily 90 readings. More inside. [more inside]

## How do I solve for a percentage of a total budget...

This will be easy for someone, but math is my second language so I'm at a loss.
How do I solve for the percentage of a TOTAL budget, when one line item is unknown (and is part of the total budget)? [more inside]

## Math Problem

Please help with this probability related math problem. [more inside]

## Help me understand the concept of "85th Percentile."

I am part of a group working on a policy document for the mitigation of traffic issues (e.g. speeding). Stakeholders are having a hard time with a particular criteria which reads as follows: "85th percentile speed is in excess of the signed speed limit by 5 mph or more." [more inside]

## Getting my hands on a Russian math book?

I'm trying to buy a copy of a famous Russian geometry textbook, Kiselev's Geometry (link to a recent English translation),

*in the original Russian*. Any copy of any edition will do; in fact, a used copy would be mildly preferred. However, I speak no Russian whatsoever, so I'm having difficulty figuring out how to go about this, partly because I don't even know what to search for on a Russian-language site! How can I complete my task? [more inside]## Balanced team schedules based on seeding

I'm running a fantasy football league in which we have 10 teams. The first 9 weeks were round-robin style, with each team playing each other team exactly once. My plan was to schedule weeks 10 through 13 (four weeks) such that each team played a mix of stronger and weaker opponents based on the standings in weeks 1 through 9, then use the week 1-13 results to seed teams for the playoffs in weeks 14-16, but I'm having trouble developing an approach for generating these balanced week 10-13 matchups fairly. Any ideas? [more inside]

## Math, sweet sweet math

I have a set of data: D(t). 5000 samples. Scatter-graphing makes some patterns clear (D-mean increases with t, for instance). D and t are always positive. I want to characterize these, statistically. [more inside]

## Essay question has too many permutations or am I overthinking this?

For my son’s high school history class, he has been assigned an in-class argument/opinion essay. The teacher ended most of the lecturing this week and has given them time to prepare thesis statements for the essays. Here is where it starts to get complicated (at least to my son and me): [more inside]

## In a 2048 or Threes-like game, what is the highest possible score?

In one of these puzzle games like 2048 or Threes, where you merge tiles to create higher numbers, is there any way to prove what is the highest possible tile number that can be created given the rules and dimensions? [more inside]

## What are inter-disciplinary and atypical uses for math MSc?

I have just completed my MSc in mathematics in Europe. I do enjoy math, but I spent my uni years feeling like a autodidact hippie marooned on an island full of Mr and Mrs I-Want-A-Good-Job. My main interests revolve around humanities (literature/history/anthropology) and economics (but not finance), and instead of starting a "stable" well-paying career I dream about something inter-disciplinary. I am very open to earning little money and relocating just to do kind of work that engages those skills. What are some random uses of my degree? [more inside]

## what percent will result from combining two types of milk?

If I add 1/100 to 2/100, I get 3/100 or 3%. But if I add one hundred apples, one of which is red, to one hundred apples, two of which are red, I will have 3/200 or 1.5%. I'm very confused now as to what percent milk fat my milk will be if I combine the two types of milk (1% and 2%) together.

## Math Filter: What is Calculus?

My son would like to know: Is there more to calculus than functions, examples of functions, various formats for presenting functions, and so on? That is, does calculus have unique to it other tools that are not just variations on functions? [more inside]

## Maximum sum of numbers, one from each set, with constraints

Working on a personal project, I am running into a number of math problems of the kind described within. I am not a math expert, so I don't know what to call these kinds of problems, so I don't know how to search for information about them. [more inside]

## Pythagorean Theorem in the original Greek

I'm looking for a textual version of

*a*^{2}+*b*^{2}=*c*^{2}that is as old as possible, among all the Greek sources. [more inside]## How do I calculate combined percentages?

Mathfail: I'm considering supplementing my cat's food with plain meat. I'd like a rough idea of how much it would bump percentage of calories from protein and fat. [more inside]

## You Can't Handle the (Next) Proof!

Working through Apostol's Calculus Volume I for personal development. Stuck on a proof, again. Can you help? [more inside]

## How to take scientific notes efficiently?

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. [more inside]

## In Need an Nerdy T-Shirt for Tomorrow (3.141592654...)

Okay, I'm in NYC and I need a PI related T-Shirt for Pi-Daytomorrow... Anyone know of any stores where I can get one? (It's too late for an online order)

## Singapore Math

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 Singapore method that he's taught in school. Note that he hasn't learned how to add negative numbers, which puts a crimp on the methodology. [more inside]

## You Can't Handle the Proof!

Working through Apostol's Calculus Volume I for personal development. Stuck on a proof. Can you help? [more inside]

## Why can't I differentiate this nomal/Guassian distrubution?

Have a look here. I'm assured that differentiating 1, with respect to

*x*, 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 produces something (that looks) very different. Can someone help me out?## Percentage Question

Help me understand percentages. [more inside]

## I need to be able to memorize several formulas for a test next week

I'm taking a numerical methods class and there are all these discretization schemes of partial differential equations named after pairs of dudes and they all are kinda the same, maybe a bit different in indexes....
I'm trying to organize it all in my head, like a frat house, with the dudes that worked on the same scheme being roommates, but it seems to be taking a long time to actually "find" a place for each scheme in their "rooms" and keeping it there in a sort of visual arrangement.
Test is no books no notes, and everything kinda of just jumbles inside my head right now.

## Studying the masters, not their pupils (budget edition)

I am a frequent buyer of <$5 books on Amazon. Lately I am interested in math treatises but have been unable to find any that aren't way out of my price range. Am I being way too demanding? [more inside]

## Math game that featured Bach and Mozart

Around 1995 I played a game on the Mac in school that was for educational purposes, supposedly for the purposes of drilling math skills, and had Mozart Symphony no. 40 (1st movement and but I think 3rd as well), Bach BWV 999, and possibly some Paganini as well, as background music. Do you know what it was?

## I want to show a movie clip in a public talk. Is this legal?

I'm giving a public talk about Goldbach's Conjecture. There is a crazy Spanish movie in which a character is famous for having proved the conjecture. Can I show a clip or two from this movie in my public talk? The talk will be in a bar, and there's a $5 suggested donation, so I don't know if that counts as charging people (if that affects the legality of my idea). Thanks!

## Modern Zoombinis?

What is the modern equivalent of 1995's lovely LOGICAL JOURNEY OF THE ZOOMBINIS computer games? They taught math logic skills rather neatly for children, but I don't have a computer that will run the old games.

## Tools For the Spatially Challenged: Couch-Movers Edition

Wizards of Hive,
Before I buy that 90" couch from a friend, how can I make sure I'll be able to get it up my L-shaped stairs? Sure, there are a lot of variables. But is there a tool or methodology for figuring this out ahead of time (presuming I know the depth and height of the couch too)? I don't think I have the cardboard to build a mockup.
This couch is 50 miles away and can't be returned. Thanks!

## Math Puzzles, Please!

"Math for Smarty Pants" was awesome -- recommend me more books like that for a kid who loves math puzzles. [more inside]

## I want to be able to read CS and math research papers with ease.

I often find myself crossing interdisciplinary lines and reading research papers, trying to understand some new practice or algorithm in math or computer science. I start out thinking "I just need to understand these basic concepts and I'll crack this", but end up with a very tired brain at 5am, having tried to mainline dense trees of Wikipedia and ~~Eric Weisstein's~~Wolfram MathWorld, and still not feeling like I retained everything. [more inside]

## Rearranging the formula for Compound Annual Growth Rate

How do you rejig the formula for CAGR to get the starting value when you know the other variables? [more inside]