diff --git a/index.js b/index.js
index 0f4b28b4..c971f628 100644
--- a/index.js
+++ b/index.js
@@ -1,17 +1,50 @@
 class SortedList {
-  constructor() {}
+  constructor() {
+    this.items = [];
+    this.length = this.items.length;
+  }
 
-  add(item) {}
+  add(item) {
+    if (typeof item === "number") {
+      this.items.push(item);
+      this.items.sort((a, b) => a - b);
+      this.length = this.items.length;
+    }
+  }
 
-  get(pos) {}
+  get(pos) {
+    if (pos >= this.length || pos < 0) {
+      throw new Error("OutOfBounds");
+    }
+    return this.items[pos];
+  }
 
-  max() {}
+  max() {
+    if (!this.length) {
+      throw new Error("EmptySortedList");
+    }
+    return Math.max(...this.items);
+  }
 
-  min() {}
+  min() {
+    if (!this.length) {
+      throw new Error("EmptySortedList");
+    }
+    return Math.min(...this.items);
+  }
 
-  sum() {}
+  sum() {
+    return this.items.reduce((sum, number) => sum + number, 0);
+  }
 
-  avg() {}
+  avg() {
+    if (!this.length) {
+      throw new Error("EmptySortedList");
+    }
+    return +(
+      this.items.reduce((sum, number) => sum + number, 0) / this.length
+    ).toFixed(1);
+  }
 }
 
 module.exports = SortedList;
diff --git a/package.json b/package.json
index 3a5127ae..701007ec 100644
--- a/package.json
+++ b/package.json
@@ -19,5 +19,8 @@
     "intro"
   ],
   "author": "fer@ironhack.com",
-  "license": "MIT"
+  "license": "MIT",
+  "dependencies": {
+    "mocha": "^11.7.6"
+  }
 }
diff --git a/test/index.spec.js b/test/index.spec.js
index 5cf5d238..8323223e 100644
--- a/test/index.spec.js
+++ b/test/index.spec.js
@@ -58,7 +58,7 @@ describe("SortedList", () => {
           list.get(4);
         },
         Error,
-        "OutOfBounds"
+        "OutOfBounds",
       );
     });
 
@@ -73,13 +73,13 @@ describe("SortedList", () => {
       list = new SortedList();
     });
 
-    it("should throw an Empty SortedList error if there are no elements in the list", () => {
+    it("should throw an EmptySortedList error if there are no elements in the list", () => {
       assert.throws(
         () => {
           list.max([]);
         },
         Error,
-        "Empty SortedList"
+        "EmptySortedList",
       );
     });
 
@@ -102,7 +102,7 @@ describe("SortedList", () => {
           list.min([]);
         },
         Error,
-        "EmptySortedList"
+        "EmptySortedList",
       );
     });
 
@@ -143,7 +143,7 @@ describe("SortedList", () => {
           list.avg([]);
         },
         Error,
-        "EmptySortedList"
+        "EmptySortedList",
       );
     });