Add initial implementation of mean calculation and tests

Author: Baba05206

prep/mean.js

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+/*
+Let’s consider a list of prices in a bill:
+4.6, 5.03, 7.99, 8.01
+instead of writing the  like below
+const price0 = 4.6;
+const price1 = 5.03;
+const price2 = 7.99;
+const price3 = 8.01;
+We can write it as an array literal
+const items = [4.6, 5.03, 7.99, 8.01];
+
+The Array object, as with arrays in other programming languages, enables storing a collection
+of multiple items under a single variable name, and has members for performing common array operations.
+Arrays can store items of any type & multiple pieces of information.
+
+In JavaScript, we can use [] notation to access specific elements in the array using index numbers.
+The index numbers start from 0.
+
+
+const items = [4.6, 5.03, 7.99, 8.01];
+console.log(items[0]); // 4.6
+console.log(items[1]); // 5.03
+console.log(items[2]); // 7.99
+console.log(items[3]); // 8.01
+// Accessing elements using index numbers
+*/
+const items = [4.6, 5.03, 7.99, 8.01];
+function calculateMean(list) {
+  // Calculate the sum of all elements in the array
+  const sum = list.reduce(
+    (accumulator, currentValue) => accumulator + currentValue,
+    0
+  );
+  // Calculate the mean by dividing the sum by the number of elements
+  const mean = sum / list.length;
+  return mean;
+}

prep/mean.test.js

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+/*
+test("does something as described below", () => {   
+    // test implementation goes here    
+});
+*/
+test("calculates the mean of a list of numbers", () => {
+  const list = [3, 50, 7];
+  const currentOutput = calculateMean(list);
+  const targetOutput = 20;
+
+  expect(currentOutput).toEqual(targetOutput); // 20 is (3 + 50 + 7) / 3
+});

prep/package.json

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+{
+  "name": "prep",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "scripts": {
+    "test": "jest"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "type": "commonjs",
+  "devDependencies": {
+    "jest": "^30.2.0"
+  }
+}