diff --git a/Chapter4_TheGreatestTheoremNeverTold/Ch4_LawOfLargeNumbers_TFP.ipynb b/Chapter4_TheGreatestTheoremNeverTold/Ch4_LawOfLargeNumbers_TFP.ipynb
index a9754bef..02790a78 100644
--- a/Chapter4_TheGreatestTheoremNeverTold/Ch4_LawOfLargeNumbers_TFP.ipynb
+++ b/Chapter4_TheGreatestTheoremNeverTold/Ch4_LawOfLargeNumbers_TFP.ipynb
@@ -1445,7 +1445,7 @@
         "def intervals(u, d):\n",
         "    a = tf.add(1., u)\n",
         "    b = tf.add(1., d)\n",
-        "    mu = tf.divide(x=a, y=tf.add(1., u))\n",
+        "    mu = tf.divide(x=a, y=tf.add(a, b))\n",
         "    std_err = 1.65 * tf.sqrt((a * b) / ((a + b) ** 2 * (a + b + 1.)))\n",
         "    \n",
         "    return (mu, std_err)\n",