diff --git a/lab-03_minimizing_cost.ipynb b/lab-03_minimizing_cost.ipynb
index d8fb794..fe77d43 100644
--- a/lab-03_minimizing_cost.ipynb
+++ b/lab-03_minimizing_cost.ipynb
@@ -266,7 +266,7 @@
     }
    ],
    "source": [
-    "gradient = torch.sum((W * x_train - y_train) * x_train)\n",
+    "gradient = torch.mean((W * x_train - y_train) * x_train)\n",
     "print(gradient)"
    ]
   },
@@ -428,7 +428,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.6.5"
+   "version": "3.7.9"
   }
  },
  "nbformat": 4,