diff --git a/Sprint-1/fix/median.js b/Sprint-1/fix/median.js
index 5c5b796e1..beeebd932 100644
--- a/Sprint-1/fix/median.js
+++ b/Sprint-1/fix/median.js
@@ -6,9 +6,30 @@
 // or contains values that aren't numbers (the function is expected to throw - see the tests).
 
 function calculateMedian(list) {
+  if (!Array.isArray(list)) {
+    throw new Error("calculateMedian requires an array of numbers");
+  }
+  if (list.length === 0) {
+    throw new Error("calculateMedian requires a non-empty array");
+  }
+
+  if (!list) {
+    throw new Error("calculateMedian requires an array of numbers");
+  }
+  for (const item of list) {
+    if (typeof item !== "number") {
+      throw new Error("calculateMedian requires an array of numbers");
+    }
+  }
   const middleIndex = Math.floor(list.length / 2);
-  const median = list.splice(middleIndex, 1)[0];
-  return median;
+  const sortedList = [...list].sort((a, b) => a - b);
+  if (list.length % 2 === 0) {
+    const median = (sortedList[middleIndex] + sortedList[middleIndex - 1]) / 2;
+    return median;
+  } else {
+    //const median = sortedList.splice(middleIndex, 1)[0];
+    return sortedList[middleIndex];
+  }
 }
 
 module.exports = calculateMedian;
diff --git a/Sprint-1/implement/dedupe.js b/Sprint-1/implement/dedupe.js
index 781e8718a..4cd6d23e7 100644
--- a/Sprint-1/implement/dedupe.js
+++ b/Sprint-1/implement/dedupe.js
@@ -1 +1,12 @@
-function dedupe() {}
+function dedupe(array) {
+  const withOutDup = [];
+  for (let i = 0; i < array.length; i++) {
+    const item = array[i];
+    if (!withOutDup.includes(item)) {
+      withOutDup.push(item);
+    }
+  }
+
+  return withOutDup;
+}
+module.exports = dedupe;
diff --git a/Sprint-1/implement/dedupe.test.js b/Sprint-1/implement/dedupe.test.js
index d7c8e3d8e..6ead2f900 100644
--- a/Sprint-1/implement/dedupe.test.js
+++ b/Sprint-1/implement/dedupe.test.js
@@ -16,13 +16,44 @@ E.g. dedupe([1, 2, 1]) returns [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.todo("given an empty array, it returns an empty array");
+test("when passed an emptyarray", () => {
+  const array = [];
+  dedupe(array);
+  expect(dedupe(array)).toEqual([]);
+});
 
 // Given an array with no duplicates
 // When passed to the dedupe function
 // Then it should return a copy of the original array
+test("when passed an array with no duplicate", () => {
+  const array = [1, 2, 3, 4];
+  dedupe(array);
+  expect(dedupe(array)).toEqual([1, 2, 3, 4]);
+});
 
 // Given an array of strings or numbers
 // When passed to the dedupe function
-// Then it should return a new array with duplicates removed while preserving the 
+// Then it should return a new array with duplicates removed while preserving the
 // first occurrence of each element from the original array.
+test("when passed an array of  duplicate numbers", () => {
+  expect(dedupe([1, 1, 2])).toEqual([1, 2]);
+  expect(dedupe([1, 1, 2, 2, 2, 3])).toEqual([1, 2, 3]);
+  expect(dedupe([1, 1, 1, 3, 3, 4, 4])).toEqual([1, 3, 4]);
+});
+
+test("when passed an array of duplicate characters", () => {
+  expect(dedupe(["a", "a", "b", "b", "b", "c"])).toEqual(["a", "b", "c"]);
+  expect(dedupe(["c", "c", "e", "e", "z", "z"])).toEqual(["c", "e", "z"]);
+});
+test("when passed an array of duplicate unordered  numbers  ", () => {
+  expect(dedupe([5, 1, 1, 2, 3, 2, 5, 8])).toEqual([5, 1, 2, 3, 8]);
+});
+test("when passed an array of duplicate unordered characters ", () => {
+  expect(dedupe(["f", "a", "a", "k", "k", "c", "c"])).toEqual([
+    "f",
+    "a",
+    "k",
+    "c",
+  ]);
+});
diff --git a/Sprint-1/implement/describe-median.js b/Sprint-1/implement/describe-median.js
index 3381cfc0a..d21712eec 100644
--- a/Sprint-1/implement/describe-median.js
+++ b/Sprint-1/implement/describe-median.js
@@ -20,6 +20,15 @@ function calculateMedian(list) {
 }
 
 // Implement this function. See describe-median.test.js for the acceptance criteria.
-function describeMedian(list) {}
+function describeMedian(list) {
+  try {
+    let result = calculateMedian(list);
+    return result;
+  } catch (error) {
+    // console.error(`Could not calculate a median:${error.message}`);
+    return `Could not calculate a median:${error.message}`;
+    //throw error;
+  }
+}
 
 module.exports = describeMedian;
diff --git a/Sprint-1/implement/describe-median.test.js b/Sprint-1/implement/describe-median.test.js
index e7d18a264..6acf2be0e 100644
--- a/Sprint-1/implement/describe-median.test.js
+++ b/Sprint-1/implement/describe-median.test.js
@@ -21,12 +21,33 @@ const describeMedian = require("./describe-median.js");
 // When passed to describeMedian
 // Then it should return "The median is " followed by the median
 // Delete this test.todo and replace it with a test.
-test.todo('given [1, 2, 3], returns "The median is 2"');
+test("returns the correct median when given [1,2,3]", () => {
+  expect(describeMedian([1, 2, 3])).toEqual(2);
+});
 
 // Given an empty array
 // When passed to describeMedian
 // Then it should return "Could not calculate a median: calculateMedian requires a non-empty array"
-
+test("returns an error message when given an empty array", () => {
+  expect(describeMedian([])).toEqual(
+    "Could not calculate a median:calculateMedian requires a non-empty array"
+  );
+});
 // Given something that isn't an array of numbers, e.g. "banana"
 // When passed to describeMedian
 // Then it should return "Could not calculate a median: calculateMedian requires an array of numbers"
+test("returns an error message when given a string of array", () => {
+  expect(describeMedian(["banana"])).toEqual(
+    "Could not calculate a median:calculateMedian requires an array of numbers"
+  );
+});
+test("return an error message when given a number", () => {
+  expect(describeMedian(123)).toEqual(
+    "Could not calculate a median:calculateMedian requires an array of numbers"
+  );
+});
+test("return an error message when given list of strings of array", () => {
+  expect(describeMedian(["one", "two", "three"])).toEqual(
+    "Could not calculate a median:calculateMedian requires an array of numbers"
+  );
+});
diff --git a/Sprint-1/implement/max.js b/Sprint-1/implement/max.js
index 6dd76378e..251ff4cd6 100644
--- a/Sprint-1/implement/max.js
+++ b/Sprint-1/implement/max.js
@@ -1,4 +1,13 @@
 function findMax(elements) {
+  if (!Array.isArray(elements)) {
+    throw new Error("findMax requires an array of numbers");
+  }
+  for (let num of elements) {
+    if (typeof num !== "number") {
+      throw new Error("findMax requires an array of numbers");
+    }
+  }
+  return Math.max(...elements);
 }
 
 module.exports = findMax;
diff --git a/Sprint-1/implement/max.test.js b/Sprint-1/implement/max.test.js
index ff3fbb5e5..7f595b755 100644
--- a/Sprint-1/implement/max.test.js
+++ b/Sprint-1/implement/max.test.js
@@ -16,28 +16,81 @@ 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("return -Infinity when given an Empty array", () => {
+  expect(findMax([])).toEqual(-Infinity);
+});
 
 // Given an array with one number
 // When passed to the max function
 // Then it should return that number
+test("return the number when given one number", () => {
+  expect(findMax([10])).toEqual(10);
+  expect(findMax([1])).toEqual(1);
+});
 
 // Given an array with both positive and negative numbers
 // When passed to the max function
 // Then it should return the largest number overall
+test("return the largest number when given negative and posetive numbers", () => {
+  expect(findMax([10, -10, -3, 4])).toEqual(10);
+  expect(findMax([-10, 2, -5, 6, 9])).toEqual(9);
+});
 
 // Given an array with just negative numbers
 // When passed to the max function
 // Then it should return the closest one to zero
+test("returns closest one to zero when given array of negative numbers", () => {
+  expect(findMax([-1, -5, -2, -10])).toEqual(-1);
+  expect(findMax([-5, -10, -100, -20])).toEqual(-5);
+});
 
 // Given an array with decimal numbers
 // When passed to the max function
 // Then it should return the largest decimal number
+test("return the largest decimal number when given decimal numbers in an array", () => {
+  expect(findMax([0.01, 0.02, 2.5, 2.9])).toEqual(2.9);
+  expect(findMax([3.5, 2.5, 2.9])).toEqual(3.5);
+  expect(findMax([10.1, 9, 3, 11])).toEqual(11);
+});
 
 // Given an array containing a value that isn't a number
 // When passed to the max function
 // Then it should throw Error("findMax requires an array of numbers")
+test("return error when given an array containg non number value", () => {
+  expect(() => findMax(["a", 2, "c"])).toThrow(
+    "findMax requires an array of numbers"
+  );
+});
+test("return error when given an array containg non number value", () => {
+  expect(() => findMax(["a", "b", "c"])).toThrow(
+    "findMax requires an array of numbers"
+  );
+});
+test("return error when given an array containg non number value", () => {
+  expect(() => findMax([1, "hallo", 2])).toThrow(
+    "findMax requires an array of numbers"
+  );
+});
+test("return error when given an array containg non number value", () => {
+  expect(() => findMax(["a", , "c"])).toThrow(
+    "findMax requires an array of numbers"
+  );
+});
+test("return error when given an array containg non number value", () => {
+  expect(() => findMax([1, , 2])).toThrow(
+    "findMax requires an array of numbers"
+  );
+});
 
 // Given something that isn't an array at all, such as "hey", 42 or no argument
 // When passed to the max function
 // Then it should throw Error("findMax requires an array of numbers")
+test("return error when given non array values", () => {
+  expect(() => findMax("hey")).toThrow("findMax requires an array of numbers");
+});
+test("return error when given non array values that is number", () => {
+  expect(() => findMax(42)).toThrow("findMax requires an array of numbers");
+});
+test("return error when given no argument", () => {
+  expect(() => findMax()).toThrow("findMax requires an array of numbers");
+});
diff --git a/Sprint-1/implement/mean.js b/Sprint-1/implement/mean.js
index 36909ea1f..2e14ef629 100644
--- a/Sprint-1/implement/mean.js
+++ b/Sprint-1/implement/mean.js
@@ -1,3 +1,20 @@
-function calculateMean(list) {}
+function calculateMean(list) {
+  if (!Array.isArray(list)) {
+    throw new Error("calculateMean requires an array of numbers");
+  }
+  if (list.length === 0) {
+    throw new Error("calculateMean requires a non-empty array");
+  }
+  for (const item of list) {
+    if (typeof item !== "number") {
+      throw new Error("calculateMean requires an array of numbers");
+    }
+  }
+  let total = 0;
+  for (const num of list) {
+    total += num;
+  }
+  return (mean = total / list.length);
+}
 
 module.exports = calculateMean;
diff --git a/Sprint-1/implement/mean.test.js b/Sprint-1/implement/mean.test.js
index 847b88676..f4b731c9f 100644
--- a/Sprint-1/implement/mean.test.js
+++ b/Sprint-1/implement/mean.test.js
@@ -23,28 +23,75 @@ const calculateMean = require("./mean.js");
 // When passed to calculateMean
 // Then it should return their mean
 // Delete this test.todo and replace it with a test.
-test.todo("given [1, 2, 6], returns 3");
+
+test("returns calculated mean when given array of numbers", () => {
+  expect(calculateMean([1, 2, 6])).toEqual(3);
+});
 
 // Given an array with a single number
 // When passed to calculateMean
 // Then it should return that number
+test("returns calculated mean when given array of numbers", () => {
+  expect(calculateMean([1])).toEqual(1);
+  expect(calculateMean([10])).toEqual(10);
+});
 
 // Given an array containing negative or decimal numbers
 // When passed to calculateMean
 // Then it should return the correct mean
+test("returns calculated mean when given array of +ve and -ve numbers and decimal numbers are given", () => {
+  expect(calculateMean([5, -2, -3, 4])).toEqual(1);
+  expect(calculateMean([-2, -1, 5])).toEqual(0.6666666666666666);
+  expect(calculateMean([1.5, 2.4, 5.6])).toEqual(3.1666666666666665);
+});
 
 // Given an empty array
 // When passed to calculateMean
 // Then it should throw Error("calculateMean requires a non-empty array")
+test("returns an error when given an empty array", () => {
+  expect(() => calculateMean([])).toThrow(
+    "calculateMean requires a non-empty array"
+  );
+});
 
 // Given a value that isn't an array, e.g. "banana", 42, null or {}
 // When passed to calculateMean
 // Then it should throw Error("calculateMean requires an array of numbers")
-
+test("throws an error when given an empty array", () => {
+  expect(() => calculateMean("banana")).toThrow(
+    "calculateMean requires an array of numbers"
+  );
+});
+test("throws an error when given a number", () => {
+  expect(() => calculateMean(42)).toThrow(
+    "calculateMean requires an array of numbers"
+  );
+});
+test("throws an error when given a null", () => {
+  expect(() => calculateMean(null)).toThrow(
+    "calculateMean requires an array of numbers"
+  );
+});
+test("throws an error when given a {}", () => {
+  expect(() => calculateMean({})).toThrow(
+    "calculateMean requires an array of numbers"
+  );
+});
 // Given no argument at all
 // When passed to calculateMean
 // Then it should throw Error("calculateMean requires an array of numbers")
+test("throws an error when given no argument", () => {
+  expect(() => calculateMean()).toThrow(
+    "calculateMean requires an array of numbers"
+  );
+});
 
 // Given an array containing a non-number value, e.g. [1, "2", 3]
 // When passed to calculateMean
 // Then it should throw Error("calculateMean requires an array of numbers")
+
+test("throws an error when given an array containing a non number value", () => {
+  expect(() => calculateMean([1, "2", 3])).toThrow(
+    "calculateMean requires an array of numbers"
+  );
+});
diff --git a/Sprint-1/implement/sum.js b/Sprint-1/implement/sum.js
index 9062aafe3..3cbe2891b 100644
--- a/Sprint-1/implement/sum.js
+++ b/Sprint-1/implement/sum.js
@@ -1,4 +1,17 @@
 function sum(elements) {
+  if (!Array.isArray(elements)) {
+    throw new Error("sum requires an array of numbers");
+  }
+  for (const num of elements) {
+    if (typeof num !== "number") {
+      throw new Error("sum requires an array of numbers");
+    }
+  }
+  let total = 0;
+  for (const num of elements) {
+    total += num;
+  }
+  return total;
 }
 
 module.exports = sum;
diff --git a/Sprint-1/implement/sum.test.js b/Sprint-1/implement/sum.test.js
index a288e0f0a..dfa22cc7d 100644
--- a/Sprint-1/implement/sum.test.js
+++ b/Sprint-1/implement/sum.test.js
@@ -13,24 +13,54 @@ 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("should return 0 when given an empty array", () => {
+  expect(sum([])).toEqual(0);
+});
 
 // Given an array with just one number
 // When passed to the sum function
 // Then it should return that number
-
+test("should return the number when given one number", () => {
+  expect(sum([10])).toEqual(10);
+  expect(sum([-1])).toEqual(-1);
+  expect(sum([0])).toEqual(0);
+});
 // Given an array containing negative numbers
 // When passed to the sum function
 // Then it should still return the correct total sum
+test("should return the number when given negative numbers ", () => {
+  expect(sum([10, -4, 5, 7])).toEqual(18);
+  expect(sum([-3, -4, -6, -9])).toEqual(-22);
+  expect(sum([7, -9, 2, 1])).toEqual(1);
+});
 
 // Given an array with decimal/float numbers
 // When passed to the sum function
 // Then it should return the correct total sum
+test("should return the number when given decimal number", () => {
+  expect(sum([2.5, 3.4, 5.5, 2])).toEqual(13.4);
+  expect(sum([1, 1.5, 2.5, 6.3])).toEqual(11.3);
+  expect(sum([2.3, 2.7, 7.4, 5.5])).toEqual(17.9);
+});
 
 // Given an array containing a value that isn't a number
 // When passed to the sum function
 // Then it should throw Error("sum requires an array of numbers")
+test("should throw an error when argument is passed that is non number", () => {
+  expect(() => sum([1, 2, "hi", 3, "hey"])).toThrow(
+    "sum requires an array of numbers"
+  );
+});
 
 // Given something that isn't an array at all, such as "hey", 42 or no argument
 // When passed to the sum function
 // Then it should throw Error("sum requires an array of numbers")
+test("should throw an error when argument 'hey'is passed", () => {
+  expect(() => sum("hey")).toThrow("sum requires an array of numbers");
+});
+test("should throw an error when argument 42 is passed", () => {
+  expect(() => sum(42)).toThrow("sum requires an array of numbers");
+});
+test("should throw an error when no argument is passed", () => {
+  expect(() => sum()).toThrow("sum requires an array of numbers");
+});
diff --git a/Sprint-1/refactor/includes.js b/Sprint-1/refactor/includes.js
index 29dad81f0..e78b21d70 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 (let num of list) {
+    if (num === target) {
       return true;
     }
   }