diff --git a/Exercises_1.ipynb b/Exercises_1.ipynb
index 4a656d2..b25b166 100644
--- a/Exercises_1.ipynb
+++ b/Exercises_1.ipynb
@@ -80,7 +80,7 @@
     "cell_type": "hint"
    },
    "source": [
-    "Why don't you try with `.mean()`"
+    "You should always aware with the <b> column name </b> as little differences would matter, it supposed to be <b>'Customer_Age'</b> not <b>'Customers_Age'<b/>. <br> Why don't you try with `.mean()`"
    ]
   },
   {