diff --git a/task-1/count-above-threshold.js b/task-1/count-above-threshold.js
index 7cf0418..6693fd2 100644
--- a/task-1/count-above-threshold.js
+++ b/task-1/count-above-threshold.js
@@ -1 +1,16 @@
 //Your code here
+function countAboveThreshold(numbers, threshold) {
+  let count = 0;
+
+  for (let i = 0; i < numbers.length; i++) {
+    if (numbers[i] > threshold) {
+      count++;
+    }
+  }
+
+  return count;
+}
+
+console.log(countAboveThreshold([1, 5, 10, 3], 4));
+console.log(countAboveThreshold([7, 8, 9], 10));
+console.log(countAboveThreshold([], 5));
diff --git a/task-2/calculateAverage.test.js b/task-2/calculateAverage.test.js
new file mode 100644
index 0000000..8a6df4f
--- /dev/null
+++ b/task-2/calculateAverage.test.js
@@ -0,0 +1,25 @@
+import { describe, test, expect } from "vitest";
+import { calculateAverage } from "./calculateAverage.js";
+
+describe("calculateAverage", () => {
+  test("returns the average for a normal array of numbers", () => {
+    expect(calculateAverage([2, 4, 6])).toBe(4);
+  });
+
+  test("returns the number itself when the array has one element", () => {
+    expect(calculateAverage([5])).toBe(5);
+  });
+
+  test("returns null for an empty array", () => {
+    expect(calculateAverage([])).toBeNull();
+  });
+
+  test("returns null when input is not an array", () => {
+    expect(calculateAverage("123")).toBeNull();
+    expect(calculateAverage(null)).toBeNull();
+  });
+
+  test("returns null when the array contains a non-number value", () => {
+    expect(calculateAverage([1, 2, "3"])).toBeNull();
+  });
+});
diff --git a/task-3/count-vowels-debug.js b/task-3/count-vowels-debug.js
index 1ce292b..5c52317 100644
--- a/task-3/count-vowels-debug.js
+++ b/task-3/count-vowels-debug.js
@@ -1,7 +1,7 @@
 function countVowels(text) {
   let count = 0;
 
-  for (let i = 0; i <= text.length; i++) {
+  for (let i = 0; i < text.length; i++) {
     if (
       text[i] === "a" ||
       text[i] === "e" ||
@@ -15,3 +15,7 @@ function countVowels(text) {
 
   return count;
 }
+console.log(countVowels("hello")); // returns 2
+console.log(countVowels("javascript")); // returns 3
+console.log(countVowels("")); // returns 0
+console.log(countVowels("Apple")); // returns 1
diff --git a/task-4/search-experiment.js b/task-4/search-experiment.js
index 63c189a..6f41107 100644
--- a/task-4/search-experiment.js
+++ b/task-4/search-experiment.js
@@ -1,3 +1,55 @@
 // Write your code here
 // Use generateBigArray to create a big array numbers.
-// Example: generateBigArray(1000000) will create an array of 1 million numbers.
\ No newline at end of file
+// Example: generateBigArray(1000000) will create an array of 1 million numbers.
+
+import generateBigArray from "./bigArray.js";
+
+function linear_search(array, target) {
+  for (let i = 0; i < array.length; i++) {
+    if (array[i] === target) return target;
+  }
+  return "unsuccessful";
+}
+
+function binary_search(array, target) {
+  let left = 0;
+  let right = array.length - 1;
+
+  while (left <= right) {
+    let middle = Math.floor(left + (right - left) / 2);
+    if (array[middle] < target) {
+      left = middle + 1;
+    } else if (array[middle] > target) {
+      right = middle - 1;
+    } else {
+      return middle;
+    }
+  }
+  return "unsuccessful";
+}
+
+const target = 123456789;
+const experiments = [
+  { size: 1000, label: "1k" },
+  { size: 100000, label: "100k" },
+  { size: 1000000, label: "1M" },
+  { size: 10000000, label: "10M" },
+];
+
+// --- Linear Search Tests ---
+experiments.forEach((exp) => {
+  const arr = generateBigArray(exp.size);
+  console.time(`Linear Search ${exp.label}`);
+  linear_search(arr, target);
+  console.timeEnd(`Linear Search ${exp.label}`);
+});
+
+console.log("---");
+
+// --- Binary Search Tests ---
+experiments.forEach((exp) => {
+  const arr = generateBigArray(exp.size);
+  console.time(`Binary Search ${exp.label}`);
+  binary_search(arr, target);
+  console.timeEnd(`Binary Search ${exp.label}`);
+});