diff --git a/Sprint-1/fix/median.js b/Sprint-1/fix/median.js
index b22590bc6..07d175c8e 100644
--- a/Sprint-1/fix/median.js
+++ b/Sprint-1/fix/median.js
@@ -5,10 +5,32 @@
 // Hint: Please consider scenarios when 'list' doesn't have numbers (the function is expected to return null)
 // 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;
+  }
+
+  // Filter non-numbers 
+  const filteredList = list.filter(
+    (item) => typeof item === "number" && !isNaN(item)
+  );
+
+  if (filteredList.length === 0) {
+    return null;
+  }
+
+  // We can safely sort filteredList directly 
+  filteredList.sort((a, b) => a - b);
+
+  const mid = Math.floor(filteredList.length / 2);
+
+  if (filteredList.length % 2 === 0) {
+    return (filteredList[mid - 1] + filteredList[mid]) / 2;
+  } 
+  else {
+    return filteredList[mid];
+  }
 }
 
 module.exports = calculateMedian;
diff --git a/Sprint-1/implement/dedupe.js b/Sprint-1/implement/dedupe.js
index 781e8718a..f40a19245 100644
--- a/Sprint-1/implement/dedupe.js
+++ b/Sprint-1/implement/dedupe.js
@@ -1 +1,17 @@
-function dedupe() {}
+function dedupe(arr) {
+  if (!Array.isArray(arr)) return null;
+
+  const seen = new Set();
+  const result = [];
+
+  for (const item of arr) {
+    if (!seen.has(item)) {
+      seen.add(item);
+      result.push(item);
+    }
+  }
+
+  return result;
+}
+
+module.exports = dedupe;
diff --git a/Sprint-1/implement/dedupe.test.js b/Sprint-1/implement/dedupe.test.js
index 23e0f8638..900cb606a 100644
--- a/Sprint-1/implement/dedupe.test.js
+++ b/Sprint-1/implement/dedupe.test.js
@@ -16,12 +16,40 @@ 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", () => {
+    const input = [];
+    const result = dedupe(input);
+
+    expect(result).toEqual([]);
+    expect(result).not.toBe(input);  
+});
 
 // Given an array with no duplicates
-// When passed to the dedupe function
-// Then it should return a copy of the original array
+// when passed to the dedupe function
+// Then should return a copy of the original array 
+test("given an array with no duplicates, it returns a copy of the original array", () => {
+    const input = [1, 2, 3];
+    const result = dedupe(input);
+
+    expect(result).toEqual([1, 2, 3]);
+    expect(result).not.toBe(input);   
+});
 
 // 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
+// when passed to the dedupe function
+// Then it returns a new array that removes duplicates preserving the first occurrence.
+test("given an array with strings or numbers, removes duplicates preserving the first occurrence", () => {
+    const cases = [
+        { input: ['a','a','a','b','b','c'], expected: ['a','b','c'] },
+        { input: [5, 1, 1, 2, 3, 2, 5, 8], expected: [5, 1, 2, 3, 8] },
+        { input: [1, 2, 1], expected: [1, 2] }
+    ];
+
+    cases.forEach(({ input, expected }) => {
+        const result = dedupe(input);
+
+        expect(result).toEqual(expected);
+        expect(result).not.toBe(input);   
+    });
+});
diff --git a/Sprint-1/implement/max.js b/Sprint-1/implement/max.js
index 6dd76378e..57359d2f0 100644
--- a/Sprint-1/implement/max.js
+++ b/Sprint-1/implement/max.js
@@ -1,4 +1,18 @@
 function findMax(elements) {
+  let max = -Infinity;
+
+  for (let i = 0; i < elements.length; i++) {
+    const value = elements[i];
+
+    // Only consider real finite numbers 
+    if (typeof value === "number" && Number.isFinite(value)) {
+      if (value > max) {
+        max = value;
+      }
+    }
+  }
+
+  return max; 
 }
 
 module.exports = findMax;
diff --git a/Sprint-1/implement/max.test.js b/Sprint-1/implement/max.test.js
index 82f18fd88..b7f7bfb96 100644
--- a/Sprint-1/implement/max.test.js
+++ b/Sprint-1/implement/max.test.js
@@ -16,28 +16,54 @@ const findMax = require("./max.js");
 // 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([33])).toBe(33);
+});
 
 // 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 both positive and negative numbers, returns the largest number overall", () => {
+    expect(findMax([-10, -20, 0, 10, 20])).toBe(20);
+});
+
 // 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 just negative numbers, returns the closest one to zero", () => {
+    expect(findMax([-10, -20, -30])).toBe(-10);
+});
+
 // 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 decimal number", () => {
+    expect(findMax([1.5, 2.5, 3.5, 2.9])).toBe(3.5);
+});
+
 // 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-number values, returns the max and ignores non-numeric values", () => {
+    expect(findMax(['hey', 10, 'hi', 60, 10])).toBe(60);
+});
+
 // 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-number values, returns -Infinity", () => {
+    expect(findMax(['hey', 'hi', 'hello'])).toBe(-Infinity);
+});
diff --git a/Sprint-1/implement/sum.js b/Sprint-1/implement/sum.js
index 9062aafe3..a77232ff2 100644
--- a/Sprint-1/implement/sum.js
+++ b/Sprint-1/implement/sum.js
@@ -1,4 +1,18 @@
 function sum(elements) {
+  // Validate input
+  if (!Array.isArray(elements)) {
+    return 0;
+  }
+
+  // Keep only valid finite numbers and accumulate them
+  let total = 0;
+  for (let i = 0; i < elements.length; i++) {
+    if (Number.isFinite(elements[i])) {
+      total += elements[i];
+    }
+  }
+
+  return total;
 }
 
 module.exports = sum;
diff --git a/Sprint-1/implement/sum.test.js b/Sprint-1/implement/sum.test.js
index dd0a090ca..b771d4bb1 100644
--- a/Sprint-1/implement/sum.test.js
+++ b/Sprint-1/implement/sum.test.js
@@ -13,24 +13,46 @@ 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 just one number, returns that number", () => {
+    expect(sum([40])).toBe(40);
+});
+
 // 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 containing negative numbers, returns the correct total sum", () => {
+    expect(sum([-10, -20, -30])).toBe(-60);
+});
+
 // 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 the correct total sum", () => {
+    expect(sum([1.5, 2.5, 3.5])).toBe(7.5);
+});
+
 // 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 containing non-number values, returns the correct total sum", () => {
+    expect(sum(['hey', 10, 'hi', 60, 10])).toBe(80);
+});
+
 // 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-number values, returns 0", () => {
+    expect(sum(['hey', 'hi', 'hello'])).toBe(0);
+});
\ No newline at end of file
diff --git a/Sprint-1/refactor/includes.js b/Sprint-1/refactor/includes.js
index 29dad81f0..6aeac0b5d 100644
--- a/Sprint-1/refactor/includes.js
+++ b/Sprint-1/refactor/includes.js
@@ -1,9 +1,8 @@
 // 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];
-    if (element === target) {
+  for (const item of list) {
+    if (item === target) {
       return true;
     }
   }