diff --git a/Sprint-1/fix/median.js b/Sprint-1/fix/median.js
index b22590bc6..16eb5d075 100644
--- a/Sprint-1/fix/median.js
+++ b/Sprint-1/fix/median.js
@@ -6,9 +6,27 @@
 // or 'list' has mixed values (the function is expected to sort only numbers).
 
 function calculateMedian(list) {
-  const middleIndex = Math.floor(list.length / 2);
-  const median = list.splice(middleIndex, 1)[0];
-  return median;
+  if (!Array.isArray(list)) {
+    return null;
+  }
+  
+  const numericValues = list.filter(item => typeof item === 'number' && !isNaN(item));
+  
+  if (numericValues.length === 0) {
+    return null;
+  }
+  
+  const sortedList = [...numericValues].sort((a, b) => a - b);
+  
+  const length = sortedList.length;
+  const middleIndex = Math.floor(length / 2);
+  
+  if (length % 2 === 1) {
+    return sortedList[middleIndex];
+  }
+  
+  return (sortedList[middleIndex - 1] + sortedList[middleIndex]) / 2;
 }
 
 module.exports = calculateMedian;
+
diff --git a/Sprint-1/implement/dedupe.js b/Sprint-1/implement/dedupe.js
index 781e8718a..2bb84c461 100644
--- a/Sprint-1/implement/dedupe.js
+++ b/Sprint-1/implement/dedupe.js
@@ -1 +1,16 @@
-function dedupe() {}
+function dedupe(elements) {
+  if (!elements || elements.length === 0) {
+    return [];
+  }
+  
+  const seen = new Set();
+  return elements.filter(element => {
+    if (seen.has(element)) {
+      return false;
+    }
+    seen.add(element);
+    return true;
+  });
+}
+
+module.exports = dedupe;
diff --git a/Sprint-1/implement/dedupe.test.js b/Sprint-1/implement/dedupe.test.js
index 23e0f8638..e8ef5d6ab 100644
--- a/Sprint-1/implement/dedupe.test.js
+++ b/Sprint-1/implement/dedupe.test.js
@@ -16,12 +16,23 @@ E.g. dedupe([1, 2, 1]) target output: [1, 2]
 // Given an empty array
 // When passed to the dedupe function
 // Then it should return an empty array
-test.todo("given an empty array, it returns an empty array");
+test("given an empty array, it returns an empty array", () => {
+  expect(dedupe([])).toEqual([]);
+});
 
 // Given an array with no duplicates
 // When passed to the dedupe function
 // Then it should return a copy of the original array
+test("given an array with no duplicates, returns a copy", () => {
+  expect(dedupe([1, 2, 3, 4])).toEqual([1, 2, 3, 4]);
+  expect(dedupe(['a', 'b', 'c'])).toEqual(['a', 'b', 'c']);
+});
 
 // Given an array with strings or numbers
 // When passed to the dedupe function
 // Then it should remove the duplicate values, preserving the first occurence of each element
+test("given an array with duplicates, removes them preserving first occurrence", () => {
+  expect(dedupe(['a','a','a','b','b','c'])).toEqual(['a','b','c']);
+  expect(dedupe([5, 1, 1, 2, 3, 2, 5, 8])).toEqual([5, 1, 2, 3, 8]);
+  expect(dedupe([1, 2, 1])).toEqual([1, 2]);
+});
diff --git a/Sprint-1/implement/max.js b/Sprint-1/implement/max.js
index 6dd76378e..62340fcbd 100644
--- a/Sprint-1/implement/max.js
+++ b/Sprint-1/implement/max.js
@@ -1,4 +1,11 @@
 function findMax(elements) {
+  const numbers = elements.filter(element => typeof element === 'number');
+  
+  if (numbers.length === 0) {
+    return -Infinity;
+  }
+  
+  return Math.max(...numbers);
 }
 
 module.exports = findMax;
diff --git a/Sprint-1/implement/max.test.js b/Sprint-1/implement/max.test.js
index 82f18fd88..048098236 100644
--- a/Sprint-1/implement/max.test.js
+++ b/Sprint-1/implement/max.test.js
@@ -15,29 +15,53 @@ const findMax = require("./max.js");
 // Given an empty array
 // When passed to the max function
 // Then it should return -Infinity
-// Delete this test.todo and replace it with a test.
-test.todo("given an empty array, returns -Infinity");
+test("given an empty array, returns -Infinity", () => {
+  expect(findMax([])).toBe(-Infinity);
+});
 
 // Given an array with one number
 // When passed to the max function
 // Then it should return that number
+test("given an array with one number, returns that number", () => {
+  expect(findMax([42])).toBe(42);
+  expect(findMax([-5])).toBe(-5);
+});
 
 // Given an array with both positive and negative numbers
 // When passed to the max function
 // Then it should return the largest number overall
+test("given an array with positive and negative numbers, returns the largest", () => {
+  expect(findMax([30, 50, 10, 40])).toBe(50);
+  expect(findMax([-10, 5, -20, 15])).toBe(15);
+});
 
 // Given an array with just negative numbers
 // When passed to the max function
 // Then it should return the closest one to zero
+test("given an array with only negative numbers, returns closest to zero", () => {
+  expect(findMax([-10, -5, -20])).toBe(-5);
+  expect(findMax([-1, -2, -3])).toBe(-1);
+});
 
 // Given an array with decimal numbers
 // When passed to the max function
 // Then it should return the largest decimal number
+test("given an array with decimal numbers, returns the largest", () => {
+  expect(findMax([1.5, 2.7, 1.9])).toBe(2.7);
+  expect(findMax([0.1, 0.3, 0.2])).toBe(0.3);
+});
 
 // Given an array with non-number values
 // When passed to the max function
 // Then it should return the max and ignore non-numeric values
+test("given an array with non-numeric values, ignores them", () => {
+  expect(findMax(['hey', 10, 'hi', 60, 10])).toBe(60);
+  expect(findMax([true, 5, null, 25, 'hello'])).toBe(25);
+});
 
 // Given an array with only non-number values
 // When passed to the max function
 // Then it should return the least surprising value given how it behaves for all other inputs
+test("given an array with only non-numeric values, returns -Infinity", () => {
+  expect(findMax(['hello', 'world', true, null])).toBe(-Infinity);
+});
diff --git a/Sprint-1/implement/sum.js b/Sprint-1/implement/sum.js
index 9062aafe3..a8e360a3e 100644
--- a/Sprint-1/implement/sum.js
+++ b/Sprint-1/implement/sum.js
@@ -1,4 +1,11 @@
 function sum(elements) {
+  if (elements.length === 0) {
+    return 0;
+  }
+  
+  return elements
+    .filter(element => typeof element === 'number')
+    .reduce((total, num) => total + num, 0);
 }
 
 module.exports = sum;
diff --git a/Sprint-1/implement/sum.test.js b/Sprint-1/implement/sum.test.js
index dd0a090ca..5d68c1ab3 100644
--- a/Sprint-1/implement/sum.test.js
+++ b/Sprint-1/implement/sum.test.js
@@ -13,24 +13,45 @@ const sum = require("./sum.js");
 // Given an empty array
 // When passed to the sum function
 // Then it should return 0
-test.todo("given an empty array, returns 0")
+test("given an empty array, returns 0", () => {
+  expect(sum([])).toBe(0);
+});
 
 // Given an array with just one number
 // When passed to the sum function
 // Then it should return that number
+test("given an array with one number, returns that number", () => {
+  expect(sum([5])).toBe(5);
+  expect(sum([42])).toBe(42);
+});
 
 // Given an array containing negative numbers
 // When passed to the sum function
 // Then it should still return the correct total sum
+test("given an array with negative numbers, returns correct sum", () => {
+  expect(sum([1, -2, 3])).toBe(2);
+  expect(sum([-5, -10, -15])).toBe(-30);
+});
 
 // Given an array with decimal/float numbers
 // When passed to the sum function
 // Then it should return the correct total sum
+test("given an array with decimal numbers, returns correct sum", () => {
+  expect(sum([1.5, 2.5, 3.0])).toBe(7);
+  expect(sum([0.1, 0.2, 0.3])).toBeCloseTo(0.6);
+});
 
 // Given an array containing non-number values
 // When passed to the sum function
 // Then it should ignore the non-numerical values and return the sum of the numerical elements
+test("given an array with non-numeric values, ignores them", () => {
+  expect(sum(['hey', 10, 'hi', 60, 10])).toBe(80);
+  expect(sum([true, 5, null, 15, 'hello'])).toBe(20);
+});
 
 // Given an array with only non-number values
 // When passed to the sum function
 // Then it should return the least surprising value given how it behaves for all other inputs
+test("given an array with only non-numeric values, returns 0", () => {
+  expect(sum(['hello', 'world', true, null])).toBe(0);
+});
diff --git a/Sprint-1/refactor/includes.js b/Sprint-1/refactor/includes.js
index 29dad81f0..8c9ae2e66 100644
--- a/Sprint-1/refactor/includes.js
+++ b/Sprint-1/refactor/includes.js
@@ -1,8 +1,7 @@
 // Refactor the implementation of includes to use a for...of loop
 
 function includes(list, target) {
-  for (let index = 0; index < list.length; index++) {
-    const element = list[index];
+  for (const element of list) {
     if (element === target) {
       return true;
     }