1119 posts tagged with math.
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In search of a math toy(?) from the 80s
I once had a blue(?) math device, but I have no idea what it was or what exactly it did. See my description and let me know if you know what this thing was. [more inside]
When you run up an escalator, is that more steps or fewer?
Say you have a really long escalator, like inside many subway stations. If you run up the steps, are you stepping on fewer steps than you do if you walk up at a fast pace? At a normal pace? Or is it the same number of steps because you're still traveling the same distance, which requires a certain number of steps to reach? Or fewer steps because you're going faster than the rate of speed of the escalator itself? Assume you're not skipping any steps on your way up.
cool function curves?
I'm working on some AI music algorithms and need mathematical curves on which to base certain aspects. What are the equations/names of some beautiful/interesting/unusual 2D function curves?
Before the second intermission we need stats help
We know that Buffalo, Montreal and Carolina have the top 3 NHL draft picks, but not the ordering. We also know that they had, in order, 18.5%, 9.5% and 3.0% chance of winning the first draft pick. Given that we know one of them did, what is each team's chance of getting the first draft pick? [more inside]
printable posters on A3/tabloid paper
I have a printer that has the capability to print on A3/Tabloid sized paper. I am looking for interesting posters/infographics/other things that I could print. The resolution should be high enough to look good on A3 paper. I am interested in math, (global) history, maps, science, but I welcome all suggestions, even for completely unrelated topics.
Help me figure out what's up with this probability question
Someone posted a probability question on Mastodon: "A, B and C toot the truth with a probability of 1/3 and lie with a probability of 2/3. A makes a toot and B toots an observation on whether or not A was tooting the truth or not. C toots that B confirmed A was truthful. What is the actual probability that A's toot was truthful?" Either I made it more complicated than it needs to be, or a lot of other people are wrong, and I suspect the former. Help me get to the bottom of this! [more inside]
Engaging Math Curriculum for 6-8 Grade
I'm trying to find an engaging math curriculum for my daughter that will take her from 6-8 grade. The one she is working from is really quite boring and unengaging, and I can hardly stand to work through it myself when I help her with it. I love math and so does she, but it's been rough. [more inside]
Can you do the math since my cat and I can’t?
I’m not actually terrible at math but I’m struggling to understand cat drug dosages and would love help with 1. doing the math and 2. understanding the math. [more inside]
Please walk me through a math problem
I was once told that "1 million seconds = 14 days, and 1 billion seconds equals 35 years." Now that I've learned about the difference between a Long Scale Billion and a Short Scale Billion, I'd like to know if this quote is correct using the Short Scale (1,000 millions = 1 billion). [more inside]
Help With a Real World Math Word Problem (Does not involve two trains)
Jimmy has leased a large number of copiers.
The monthly lease cost of the copier contract is X which includes Y color impressions and Z black impressions per month. Color impressions over Y are billed at Yo per impression
Black impressions over Z are billed at Zo per impression.
What equation does Jimmy use to determine the actual per page cost for both color and black when given the monthly page counts for color and black.
Combining 'things' in different ratios
I have $10000 to spend on plants (well I wish I did anyway).
My plants come in two sizes which I'll call thing1 and thing2. [more inside]
Simple explanation of dimensional space
Years ago I read an explanation on how to think simply about dimensions from the 5th and higher. I'm trying to find it again, or the theory which describes it. [more inside]
It's 600 times sweeter than sugar, so help me dilute this.
I bought some pure sucralose and I would like to make it into something usable. Help me figure that out. [more inside]
What school to get Math MS - impact on getting CC teaching job?
I have an undergraduate degree in math and want to get a masters so I can teach community college. I’m choosing between three Tier 2 universities in Arizona - ASU, UA, NAU - that all come w teaching assistantships. The programs are virtually indistinguishable except one (NAU) offers a 2nd non-thesis track with coursework emphasizing Teaching Community College Mathematics. How much, if at all, will my choice influence community college hiring decisions?
What is new in your field?
I want to know what the new areas of research, or new discoveries, are in your field. Things such as CRISPR in biology. I'm interested in all fields, not just the sciences, but I'm especially interested in math and sciences.
I also want to know where to go to hear more news about new discoveries. I read Quanta Magazine occasionally. Where else should I be looking? I want to be reading accurate sources, both shorter sources and ones that go more into depth.
Calculating significant digits for acreage
How does one calculate the number of significant digits to use for acreage when combining several map layers and one has a very low accuracy? [more inside]
STEM nonfiction by Black, Latinx, Native authors
Just what it says in the title. I’m looking for good science writing or mathematical books by Black, Latinx, and Native/Indigenous authors. Any topic fine— popular science/math preferred but not required, so if you’ve got some super technical dissertation that’s just the best, hit me!
I'm self-teaching math. Help me pick out a graphing calculator! (+more)
I always hated math growing up. It didn't come to me naturally, took a lot of work, and I didn't have the most supportive teachers. As an adult, I'm giving myself a second chance at learning this stuff! Help me pick out a graphing calculator – and I'd love any tips or advice from anyone who may have done this too. [more inside]
Board games for practicing math skills
Can you recommend some board games for teaching/practicing elementary-aged math skills or mathematical thinking to our 7yo? Bonus points if they're also interesting for adults, double bonus points if they're not also explicitly about teaching math skills. [more inside]
Pressure canning: convert from 16oz jars to 4oz jars?
Friend of mine is canning some low-acid veg from raw, and the recipe she has recommends, let's say 20 minutes in the pressure canner for 16oz jars, and 25 minutes for quart jars. She wants to can this stuff in 4oz jars. The recipe relies on cooking time in the pressure canner, so presumably overcooking it would be Bad Somehow. What's the algorithm she would use to find out how long to pressure can 4oz jars?
Public librarian seeks statistics input
What information and statistical tests do I use to find out if moving biographies to their own special display actually increased their popularity? I want to take a rigorous approach that includes confidence levels. [more inside]
Fair way of dividing assets / drawing straws
I need to divide estate assets between 3 siblings who will not agree on anything. [more inside]
Favorite Informational YouTube Channels?
I'm looking for your favorite YouTube channels to follow that are informational, educational, or historical in nature. I'm not interested in channels that are primarily comedic, but it's fine if they're humorous while being informative. [more inside]
Someone doesn't understand how milk fat percentages work, but who?
At the grocery store today I saw two cartons of cream side-by-side. One was half & half cream and labelled 10% milk fat and the other was light cream and labelled 5% milk fat. The light cream also stated it had "33% less fat than our 10% cream". Shouldn't that be 50%? Picture of the cartons in question. [more inside]
Weil at heart
Can you recommend a good book about Simone Weil, possibly also about her brother Andre? [more inside]
What part of speech are mathematic operands?
I just heard a colleague mumble a change order number in Spanish, his native language. He said, "Numbers are the one thing I still have to do in Spanish - I learned tres mas cuatro es siete, not three plus four."
Which got me to thinking, what part of speech are math operands? They're telling you to do something (verb) but they don't conjugate. Are they a conjunction? Something weird?
How to calculate the temp of falling water?
I'm curious how much the temperature of hot water (say, 37ºC) drops as it falls through the air, like in a shower. I don't know enough physics or fluid dynamics to even know where to start googling the problem, but if you had a shower 2m off the ground, and assumed ideal large drops, how much would the water temp drop after falling say, a meter in height? [more inside]
What to do with old math textbooks?
My father in law is a retired math professor, and has a number of math textbooks he is trying to get rid of. He is looking for somewhere to donate them "where they'll be more useful than just recycling them." Is there anything he can do with them/anywhere he can donate them? [more inside]
Math assistance: Building a tesseract/hypercube model
Howdy Hive Mind! I'm planning on making a nested cube version of the hypercube/tesseract model in glass. The inner and outer cube measurements are easy, I know the angles of the diagonal pieces are 45 degrees, but for the life of me I can't figure out their length.
Let's say the outer cube is 6" on a side and the inner cube is 3", what are the lengths of the connectors?
How do I convert per capita to actual numbers?
With all the talk with gun deaths going on, I wanted to figure out in real numbers, how many people die in different countries to guns. The common statistic used is gun deaths per 100,000 people.
I know for example if there are 50 deaths in a population of 800,000, you get .0000625. Move the decimal point over 4 places to get a rate of 6.25 per 100,000 people.
Using those same numbers, how do you get to 50 deaths, knowing the population is 800,000 with a rate of 6.25? I'm sure this is probably basic algebra, but the answer eludes me!
When would it be possible to completely lose a sense of rhythm?
In wondering whether my dog enjoys having his paws moved to the beat of a song, I wondered whether one can have a sense of rhythm without a sense of math? Or, can one lack a sense of rhythm completely? I guess another way of saying this is: is there an equivalent of colorblindness for rhythm? Not just a tone-deafness, but a complete inability to perceive it? If so, what causes it? It seems to me like it should be related to the ability to understand math, but maybe it is something else? [more inside]
What does a tilde (~) in front of a number mean to a non-mathy person?
If you don't normally identify as a science/math/engineering type, how would your interpret the meaning of a tilde symbol in front of a number in a friend's text message? [more inside]
What are the final concentrations after mixing these two solutions?
If I mix 15 mL of solution A consisting of 5 mg/mL of compound A, with 15 mL of solution B consisting of 5 mg/mL of compound B, what will be my final concentrations of compounds A and B in the resulting 30 mL volume? Similarly, what if I mix 15 mL of solution A with 15 mL of solution C consisting of 2.1 mg/mL of compound A and 5 mg/mL of compound B. [more inside]
Is This Bathroom Occupied?
The other week there was a puzzle on FiveThirtyEight about the probability of the sign on a bathroom being correct given the behavior of different people in an office (solution). Can you help me figure out why my approach doesn't work? [more inside]
Relearning Math concepts again as an adult
I am looking for a good book and/or resources to revisit all major mathematical concepts. I am not looking for an all academic kind of in depth book but one that would be inspiring, cover breadth and let me dig further into a specific concept more. I have a technology background but to be honest i have forgotten mathematics.
Determining the ranking of a series of items?
I have a set of items that people have voted on and given a score out of 10. For the sake of discussion, let's say they're movies. What's the best way to use those votes to determine a list of the top 10 movies? [more inside]
Calculating a correlation
Metafilter statisticians: I have a correlation coefficient (Pearson's r) reflecting the association between two continuous variables for N = 100 people. I also have a correlation coefficient for those same variables for a subsample of that sample (n = 40). Is it possible to calculate the value of r for the remaining people in the sample (n = 60) with this information?
GRE Math-Tastrophe with a fine dusting of snowflake
I have a significant, documented math learning disability. I took the GRE in 2010 after extensive study with a tutor and time and a half as well as full use of a calculator. The result: A perfect score on the verbal and writing. 5th percentile on quant. It was kind of devastating.
For * reasons* it looks like I need to take the new GRE again in about two weeks. I will not have any accommodations available to me. It seems like the revisions to the test have made it much more difficult on the math side. I need help weighing my options...more below.
More below... [more inside]
Job for an easily distracted mathy person
I've recently decided to leave my PhD program in Educational Statistics, and so I'm out on the job market after many (MANY) years of being a Student Forever. I'm feeling a little lost about what kinds of work to even start looking for, and I'm hoping the hive mind might have some interesting ideas to jump-start the process. [more inside]
How many unique QR codes are possible?
So this question was discussed and researched at length over breakfast. However no answer was found on the internet. We also lack the fundamental math skills to calculate it ourselves. How many ways can all the little squares be combined to make a QR code?
Are there simple, non-higher-ed math certificate programs?
Recently as a sort of hobby I have picked up several certificates in areas of interest. I really enjoy learning a new thing and then getting a certificate I can hang on my wall. The cost of these certificates has ranged from $100 to $700, they took from 1-3 months each, and I completed them online with minimal bureaucracy. With that done, I'm wondering if there's anything like this for mathematics. [more inside]
Are you an engineer or an engineern't
In other words, why am I good at abstract & theoretical math and so horrible at applied/computational math? [more inside]
What homeschool program worked best for you and your child?
We are investigating homeschool programs for our 13 year old. We want some help as far as workbooks or textbooks and I definitely need help in quizzes and tests (with the answers). But at the same time, we don't want an online program where the online teacher is giving us deadlines and we also do not want them grading our child, even if it is for 30 percent of the grade. [more inside]
Career question: museum and math edition
I'm about to graduate with a master's in museum studies. I'm doing a master's project on lesson plans highlighting the math within art pieces at a specific museum. My undergraduate background is not math, but I've become interested in learning more math. [more inside]
Excel (or other program) to find specific totals out of a list?
I have a list of charges and need to figure out which went through based on the total. Can Excel do this? Could a different program? Example below. [more inside]
Hex Map Math
I'm totally blind, and interested in a number of tabletop games which use hexes to regulate movement. I don't have an actual tactile map at this point, but have a giant Excel spreadsheet which is a somewhat cumbersome equivalent. I'm wondering about mathematical ways to tell the distance between two hexes, given (X, Y) coordinates, and determine what hexes are in, say, a 60-degree arc from a sepcific hex? [more inside]
Buoyancy question
i want to put an inflatable pool in my small backyard. Then I want to fill it with water and lie on its surface on an inflatable chaise/raft thing. [more inside]
When will the Sun shine on Sunshine?
My four story apartment building is about 15 feet from a nearly identical four story apartment building to the south. I live on the third floor, and my apartment windows face south into the space between the buildings. Today at midday I can see the sun shining fully on the windows of the fourth floor apartment above mine, with the shadow from the other building starting just below their windows. How many days until it starts shining into my apartment and onto my cat? [more inside]
Data Munge: Uknown combination of 7 numbers produces a given number.
Data Munging Pros: In a spreadsheet with ten data columns, Column "A" is related to columns "B" through "J" in that some unknown combination or interaction of some or all of them will produce the data in Column "A". How do we determine what that combination is? (I can't even find what this type of problem is called, and I've not been able to find any productive Google search terms.) A more thorough explanation/example is provided in-thread. [more inside]
I am the auntie in charge of turning the kid into a nerd.
A low-income, uneducated friend of mine is utterly, utterly terrified that her 14-month-old baby will continue the cycle of poverty and become a statistic. Specifically, she wants help ensuring that he learns to read, write, and do math on schedule. Difficulty level: the only time she has to do pre-reading and pre-math activities with him is during their twice-daily 3 hour train commute while she's exhausted. [more inside]