diff --git a/.gitignore b/.gitignore
index 8ee70353f..ac74be127 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,3 +4,4 @@ node_modules
 **/.DS_Store
 .idea
 package-lock.json
+/prep/
diff --git a/Sprint-1/fix/median.js b/Sprint-1/fix/median.js
index 5c5b796e1..8a58f7c90 100644
--- a/Sprint-1/fix/median.js
+++ b/Sprint-1/fix/median.js
@@ -6,9 +6,26 @@
 // or contains values that aren't numbers (the function is expected to throw - see the tests).
 
 function calculateMedian(list) {
-  const middleIndex = Math.floor(list.length / 2);
-  const median = list.splice(middleIndex, 1)[0];
-  return median;
+  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.every((number) => typeof number === "number")) {
+    throw new Error("calculateMedian requires an array of numbers");
+  }
+  const sortedList = [...list];
+  sortedList.sort((a, b) => a - b);
+  const middleIndex = Math.floor(sortedList.length / 2);
+
+  if (sortedList.length % 2 === 0) {
+    return (sortedList[middleIndex - 1] + sortedList[middleIndex]) / 2;
+  } else {
+    return sortedList[middleIndex];
+  }
 }
 
 module.exports = calculateMedian;
diff --git a/Sprint-1/implement/dedupe.js b/Sprint-1/implement/dedupe.js
index 781e8718a..16b3eb20b 100644
--- a/Sprint-1/implement/dedupe.js
+++ b/Sprint-1/implement/dedupe.js
@@ -1 +1,18 @@
-function dedupe() {}
+function dedupe(numbers) {
+  //function starts
+  const uniqueNumbers = [];
+
+  for (let i = 0; i < numbers.length; i++) {
+    // for loop starts
+    const currentValue = numbers[i];
+
+    if (!uniqueNumbers.includes(currentValue)) {
+      // if statement starts
+      uniqueNumbers.push(currentValue);
+    } // if statement ends
+  } // for loop ends
+
+  return uniqueNumbers;
+} //function ends
+
+module.exports = dedupe;
diff --git a/Sprint-1/implement/describe-median.js b/Sprint-1/implement/describe-median.js
index 3381cfc0a..a56e3d7ba 100644
--- a/Sprint-1/implement/describe-median.js
+++ b/Sprint-1/implement/describe-median.js
@@ -1,5 +1,7 @@
 // Don't change this function.
 function calculateMedian(list) {
+
+
   if (!Array.isArray(list)) {
     throw new Error("calculateMedian requires an array of numbers");
   }
@@ -20,6 +22,13 @@ function calculateMedian(list) {
 }
 
 // Implement this function. See describe-median.test.js for the acceptance criteria.
-function describeMedian(list) {}
+function describeMedian(list) { // opens function
+  try { // opens try statement
+    const median = calculateMedian(list);
+    return `The median is ${median}`;
+  } catch (error) { // opens catch 
+    return "Could not calculate a median: " + error.message;
+  }
+} //closes function
 
 module.exports = describeMedian;
diff --git a/Sprint-1/implement/describe-median.test.js b/Sprint-1/implement/describe-median.test.js
index e7d18a264..0696112ee 100644
--- a/Sprint-1/implement/describe-median.test.js
+++ b/Sprint-1/implement/describe-median.test.js
@@ -21,12 +21,25 @@ 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('given [1, 2, 3], returns "The median is 2"', () => {
+  expect(describeMedian([1, 2, 3])).toEqual("The median is 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("given an empty array returns an error message", () => {
+  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("given a string returns an error message", () => {
+  expect(describeMedian("banana")).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..663218659 100644
--- a/Sprint-1/implement/max.js
+++ b/Sprint-1/implement/max.js
@@ -1,4 +1,20 @@
 function findMax(elements) {
+  if (
+    !Array.isArray(elements) ||
+    !elements.every((element) => typeof element === "number")
+  ) {
+    throw new Error("findMax requires an array of numbers");
+  }
+
+  let max = -Infinity;
+
+  for (let i = 0; i < elements.length; i++) {
+    if (elements[i] > max) {
+      max = elements[i];
+    }
+  }
+
+  return max;
 }
 
 module.exports = findMax;
diff --git a/Sprint-1/implement/max.test.js b/Sprint-1/implement/max.test.js
index ff3fbb5e5..21f25ffe7 100644
--- a/Sprint-1/implement/max.test.js
+++ b/Sprint-1/implement/max.test.js
@@ -16,28 +16,56 @@ 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, should return -Infinity", () => {
+  expect(findMax([])).toEqual(-Infinity);
+});
 
 // Given an array with one number
 // When passed to the max function
 // Then it should return that number
+test("expects findMax with an array containing 7 to return 7", () => {
+  expect(findMax([7])).toEqual(7);
+});
 
 // Given an array with both positive and negative numbers
 // When passed to the max function
 // Then it should return the largest number overall
-
+test("returns largest number given an array with both positive and negative numbers", () => {
+  expect(findMax([-5, -6, 10, 4])).toEqual(10);
+});
 // Given an array with just negative numbers
 // When passed to the max function
 // Then it should return the closest one to zero
-
+test("returns largest number when given an array with negative numbers", () => {
+  expect(findMax([-4, -7, -9, -14])).toEqual(-4);
+});
 // Given an array with decimal numbers
 // When passed to the max function
 // Then it should return the largest decimal number
-
+test("returns largest number when given an array of decimal numbers", () => {
+  expect(findMax([2.2, 4.3, 6.8, 9.4])).toEqual(9.4);
+});
 // 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("given an array containing a value that isn't a number", () => {
+  expect(() => findMax([4, "hello", 5])).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("given something that isn't an array at all", () => {
+  expect(() => findMax("hey")).toThrow(
+    "findMax requires an array of numbers"
+  );
+
+  expect(() => findMax(42)).toThrow(
+    "findMax requires an array of numbers"
+  );
+
+  expect(() => findMax()).toThrow(
+    "findMax requires an array of numbers"
+  );
+});
\ No newline at end of file
diff --git a/Sprint-1/implement/mean.js b/Sprint-1/implement/mean.js
index 36909ea1f..f8e710d29 100644
--- a/Sprint-1/implement/mean.js
+++ b/Sprint-1/implement/mean.js
@@ -1,3 +1,18 @@
-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");
+  }
+  if (!list.every((number) => typeof number === "number")) {
+    throw new Error("calculateMean requires an array of numbers");
+  }
+  const sum = list.reduce((sum, number) => {
+    return sum + number;
+  }, 0);
+
+  return sum / list.length;
+}
 
 module.exports = calculateMean;
diff --git a/Sprint-1/implement/mean.test.js b/Sprint-1/implement/mean.test.js
index 847b88676..1b716ae38 100644
--- a/Sprint-1/implement/mean.test.js
+++ b/Sprint-1/implement/mean.test.js
@@ -23,28 +23,63 @@ 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("given the array [1,2,6], should return the number 3", () => {
+  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("given an array with a single number, should return 7", () => {
+  expect(calculateMean([7])).toEqual(7);
+});
 
 // Given an array containing negative or decimal numbers
 // When passed to calculateMean
 // Then it should return the correct mean
-
+test("given an array of negative numbers, should return -4", () => {
+  expect(calculateMean([-2, -4, -6])).toEqual(-4);
+});
+test("given an array of decimal numbers, should return 2.5", () => {
+  expect(calculateMean([1.5, 2.5, 3.5])).toEqual(2.5);
+});
 // Given an empty array
 // When passed to calculateMean
 // Then it should throw Error("calculateMean requires a non-empty array")
-
+test("given an empty array, should throw an error", () => {
+  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("given a value that isn't an array, should throw an error", () => {
+  expect(() => calculateMean("banana")).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")
+  expect(() => calculateMean(42)).toThrow(
+    "calculateMean requires an array of numbers"
+  );
+
+  expect(() => calculateMean(null)).toThrow(
+    "calculateMean requires an array of numbers"
+  );
+
+  expect(() => calculateMean({})).toThrow(
+    "calculateMean requires an array of numbers"
+  );
 
+  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("given an array containing a non-number value, should throw an error", () => {
+  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..9fde47645 100644
--- a/Sprint-1/implement/sum.js
+++ b/Sprint-1/implement/sum.js
@@ -1,4 +1,13 @@
 function sum(elements) {
+  if (!Array.isArray(elements)) {
+    throw new Error("sum requires an array of numbers");
+  }
+  if (!elements.every((element) => typeof element === "number")) {
+    throw new Error("sum requires an array of numbers");
+  }
+const sum = elements.reduce((sum, number) => {
+    return number + sum;
+  }, 0);
+  return sum;
 }
-
 module.exports = sum;
diff --git a/Sprint-1/implement/sum.test.js b/Sprint-1/implement/sum.test.js
index a288e0f0a..94a78e0af 100644
--- a/Sprint-1/implement/sum.test.js
+++ b/Sprint-1/implement/sum.test.js
@@ -13,24 +13,49 @@ 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([])).toEqual(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([7])).toEqual(7);
+});
 
 // 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 the correct sum", () => {
+  expect(sum([-4, -6, -2])).toEqual(-12);
+});
 
 // 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 sum", () => {
+  expect(sum([2.5, 3.5, 5.5])).toEqual(11.5);
+});
 
 // 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("given an array containing a non-number, throws an error", () => {
+  expect(() => sum([10, "hello", 2])).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("given a non-array input, throws an error", () => {
+  expect(() => sum("hello")).toThrow("sum requires an array of numbers");
+});
+
+test("given no argument, throws an error", () => {
+  expect(() => sum()).toThrow("sum requires an array of numbers");
+});
+test("given a number instead of an array, throws an error", () => {
+  expect(() => sum(42)).toThrow("sum requires an array of numbers");
+});
diff --git a/Sprint-1/refactor/includes.js b/Sprint-1/refactor/includes.js
index 29dad81f0..78bbc70b0 100644
--- a/Sprint-1/refactor/includes.js
+++ b/Sprint-1/refactor/includes.js
@@ -1,8 +1,6 @@
 // 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;
     }