https://math.codidact.com/categories/41/feedNew Posts - Q&A - MathematicsMathematics - Codidact2020-10-25T02:56:32Zhttps://math.codidact.com/questions/278141The probability distribution of rolling $n$ dice and keeping $k$ highesttommihttps://math.codidact.com/users/534072020-09-19T17:57:38Z2020-10-25T02:56:32Z<p>In many roleplaying games one rolls a handful of dice and calculates their sum. In some games there are bonus or penalty dice, so that we roll, for example, 4 dice with six sides and take the su...https://math.codidact.com/questions/278629Why does the decimal expansion of $1/(10n - 1)$ have this neat pattern?Abheri Ragamhttps://math.codidact.com/users/535162020-10-19T19:07:53Z2020-10-24T01:27:32Z<p>I was playing around with the reciprocals of some positive integers and found these interesting patterns:</p>
<p>$$
\frac{1}{19} = 0.\overline{052631578947368421}
$$</p>
<p>Now, this repeating d...https://math.codidact.com/questions/278696Equation of a line given some parametrized points on it and an areamsh210https://math.codidact.com/users/81062020-10-21T13:56:43Z2020-10-21T13:56:49Z<p>My kid has this question for homework:</p>
<blockquote>
<p>A line passing through the point $(6,6)$ crosses the line $y=2x$ at the point $A$, and the $x$-axis at the point $B$ (the $x$-coordinat...https://math.codidact.com/questions/278647Method to calculate the area of a cyclic n-gonRazetimehttps://math.codidact.com/users/533102020-10-20T08:40:27Z2020-10-20T09:15:01Z<p>The area of a cyclic quadriateral, given the side lengths, is given as follows:
$$
\sqrt{(s-a)(s-b)(s-c)(s-d)}
$$</p>
<p>(Brahmagupta's formula)</p>
<p>Where $
s = \frac{a+b+c+d}{2}.
$</p>
<p>I ...https://math.codidact.com/questions/278545Using maximum of forecasted values to forecast maximumGuilherme Costahttps://math.codidact.com/users/534532020-10-16T08:57:55Z2020-10-18T07:06:15Z<p>I am using an algortihm to generate a daily sales forecast and have concluded that the forecast is, for pratical purposes, of good enough quality ("low" wMAPE).</p>
<p>In general, and ...https://math.codidact.com/questions/278558When and how should the $Z_n^2$ statistic be used?HDE 226868https://math.codidact.com/users/363722020-10-16T20:10:54Z2020-10-17T16:36:57Z<p>I was reading a paper (<a href="https://arxiv.org/abs/2010.06638">Kuechel et al. 2020</a>) claiming a detection of a high-frequency periodic signal coming from a known pulsar.<sup class="footnot...https://math.codidact.com/questions/278553Which of the multiple definitions of correlation to use?Mithrandir24601https://math.codidact.com/users/81622020-10-16T16:21:29Z2020-10-17T15:32:48Z<p>In optics<sup class="footnote-ref"><a href="#fn1" id="fnref1">1</a></sup>, we have a notion of <a href="https://en.wikipedia.org/wiki/Degree_of_coherence#Degree_of_first-order_coherence">coheren...https://math.codidact.com/questions/278464Discrete data: Graphs and skewnessNezar https://math.codidact.com/users/534712020-10-11T13:49:32Z2020-10-15T10:49:47Z<p>I am studying an introductory course in statistic " Essentials of Statistics".
The author mentioned that Histograms are used to represent the frequency distribution of a contiuous data...https://math.codidact.com/questions/278430Existence of a set of all setsMathPhysicshttps://math.codidact.com/users/532052020-10-09T08:44:55Z2020-10-10T16:55:08Z<p>Suppose that we have an axiomatic set theory having the following axiom:</p>
<p><strong>The Axiom Schema of Comprehension:</strong> Let $\mathbf{P}(x)$ be a property of $x$. For any set $A$, the...https://math.codidact.com/questions/278419Can we adapt Furstenberg's proof of the infinitude of primes to other interesting subsets of the integers?HDE 226868https://math.codidact.com/users/363722020-10-08T13:41:07Z2020-10-09T01:22:39Z<p>In a textbook, I was introduced to <a href="https://en.wikipedia.org/wiki/Furstenberg%27s_proof_of_the_infinitude_of_primes">Furstenberg's topological proof of the infinitude of primes</a>, whic...https://math.codidact.com/questions/278332Cutting the squareGrovehttps://math.codidact.com/users/534522020-10-01T21:53:10Z2020-10-07T15:22:09Z<p>I don't know how simple/diffcult this is, but it has been on my mind for some time, and I haven't managed to do anything about it, so now I'll try here to see if anyone has any input.</p>
<p>Let...https://math.codidact.com/questions/278337Similar triangles with the same areamsh210https://math.codidact.com/users/81062020-10-02T09:50:57Z2020-10-05T02:25:00Z<p>My kid was assigned this problem:</p>
<blockquote>
<p>Given</p>
<p><img src="https://math.codidact.com/uploads/N4FMPUuM5TMaqhhKXksq66mg" alt="line segments ADB, AEC, COE, and BOE;" /></p>
<p>$\o...https://math.codidact.com/questions/278331Including Association Analysis results into existing Classification ModelGuilherme Costahttps://math.codidact.com/users/534532020-10-01T21:13:15Z2020-10-01T21:13:15Z<p>I have trained a <strong>classification model</strong> that predicts (returns a score) on how likely a customer is to buy from our company.
This model <strong>does not contain any product specif...https://math.codidact.com/questions/278268Asymptotics of counting integers by prime signaturePeter Taylorhttps://math.codidact.com/users/363562020-09-28T14:30:12Z2020-09-29T07:34:22Z<p>The prime counting function $\pi(n)$ which counts the number of primes up to $n$ is well-known, and it's also fairly well-known that using a well-optimised implementation of the <a href="https:/...https://math.codidact.com/questions/278280Can we constructively find a third element of a set $X$ satisfying $X \cong X \times X$ given two distinct elements?Derek Elkinshttps://math.codidact.com/users/533982020-09-29T01:50:02Z2020-09-29T01:50:02Z<p>Consider a set $X$ such that $X \cong X\times X$. It's quite easy to prove in a classical set theory, e.g. <strong>ZF</strong>, that $X$ must be the empty set or a singleton set or an infinite s...https://math.codidact.com/questions/278140Computational hardness of the uniform halting problemuser53100https://math.codidact.com/users/531002020-09-18T17:12:41Z2020-09-20T22:17:46Z<p>How hard is the decision-problem of a plain Turing Machine halting on all inputs? I'm not sure of the terminology, but by "hard" I mean its location on the arithmetical hierarchy.</p>
...