diff --git a/education/statistics/random-variable.html b/education/statistics/random-variable.html
index 8e9232a..ff64728 100644
--- a/education/statistics/random-variable.html
+++ b/education/statistics/random-variable.html
@@ -2,7 +2,7 @@
 title: 隨機變數 (Random Variable)
 description: 
 published: true
-date: 2025-12-28T17:26:00.527Z
+date: 2025-12-28T17:29:56.513Z
 tags: 
 editor: ckeditor
 dateCreated: 2025-12-28T16:41:51.938Z
@@ -12,6 +12,7 @@ dateCreated: 2025-12-28T16:41:51.938Z
 <h3><span style="font-family:Arial, Helvetica, sans-serif;">Probability Mass Function (PMF)</span></h3>
 <p><span style="font-family:Arial, Helvetica, sans-serif;">A set of probability value <strong>p<sub>i</sub></strong> assigned to each of the values taken by the discrete random variables <strong>x<sub>i</sub></strong>.</span></p>
 <p>$0 \leq p_i \leq 1$ and $\sum_{p_i} = 1$</p>
+<p><code>$0 \leq 1$</code></p>
 <p><br><span style="font-family:Arial, Helvetica, sans-serif;">Probability</span><br>$P(X = x) = p_i$</p>
 <p><span style="font-family:Arial, Helvetica, sans-serif;">Expectation</span><br>&nbsp;</p>
 <h3><span style="font-family:Arial, Helvetica, sans-serif;">Cumulative Distribution Function (CDF)</span></h3>