58 lines
1.1 KiB
Markdown
58 lines
1.1 KiB
Markdown
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---
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id: 594da033de4190850b893874
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title: Averages/Root mean square
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challengeType: 5
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forumTopicId: 302228
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dashedName: averagesroot-mean-square
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---
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# --description--
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Compute the [Root mean square](<https://en.wikipedia.org/wiki/Root mean square> "wp: Root mean square") of the numbers 1 through 10 inclusive.
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The *root mean square* is also known by its initials RMS (or rms), and as the **quadratic mean**.
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The RMS is calculated as the mean of the squares of the numbers, square-rooted:
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$$x\_{\\mathrm{rms}} = \\sqrt {{{x_1}^2 + {x_2}^2 + \\cdots + {x_n}^2} \\over n}. $$
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# --hints--
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`rms` should be a function.
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```js
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assert(typeof rms === 'function');
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```
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`rms([1, 2, 3, 4, 5, 6, 7, 8, 9, 10])` should equal `6.2048368229954285`.
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```js
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assert.equal(rms(arr1), answer1);
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```
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# --seed--
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## --after-user-code--
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```js
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const arr1 = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
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const answer1 = 6.2048368229954285;
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```
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## --seed-contents--
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```js
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function rms(arr) {
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}
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```
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# --solutions--
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```js
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function rms(arr) {
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const sumOfSquares = arr.reduce((s, x) => s + x * x, 0);
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return Math.sqrt(sumOfSquares / arr.length);
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}
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```
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