From 13d703a5e166455fecafc2f24bbbd233bb7791a1 Mon Sep 17 00:00:00 2001
From: phidias <phidias@aperx.org>
Date: Sun, 28 Dec 2025 17:12:39 +0000
Subject: [PATCH] docs: update education/statistics/random-variable

---
 education/statistics/random-variable.md | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/education/statistics/random-variable.md b/education/statistics/random-variable.md
index 9212555..eea59c0 100644
--- a/education/statistics/random-variable.md
+++ b/education/statistics/random-variable.md
@@ -2,7 +2,7 @@
 title: 隨機變數 (Random Variable)
 description: 
 published: true
-date: 2025-12-28T17:09:49.339Z
+date: 2025-12-28T17:12:39.067Z
 tags: 
 editor: markdown
 dateCreated: 2025-12-28T16:41:51.938Z
@@ -34,5 +34,6 @@ $\int f(x) \,dx\ = 1$
 ### Cumulative Distribution Function (CDF)
 
 $F(X) = P(X \leq x) = \int_{-\infty}^{x} f(y) \,dy\\$
-
-
+$f(X) = \frac{dF(x)}{dx}$
+$P(a < x \leq b) = P(X \leq b) - P(X \leq a) = F(b) - F(a)$
+$P(a < x \leq b) = P(a \leq x \leq b)$