diff --git a/docs/1b/ece108.md b/docs/1b/ece108.md
index d2e2542..779f4fd 100644
--- a/docs/1b/ece108.md
+++ b/docs/1b/ece108.md
@@ -884,3 +884,30 @@ The **inclusion-exclusion principle** also applies.
 
 $$Pr\{A\cup B\}=Pr\{A\}+Pr\{B\}-Pr\{A\cup B\}$$
 
+### Named PDFs
+
+!!! definition
+    - An **emperical PDF** is collected from empirical data.
+
+A **Bernouilli trial** is an event with exactly two options, pass $P$ with probability $p$, or fail $F$ with probability $q=1-p$. For the event $X$:
+
+$$
+Pr\{X\}=\begin{cases}
+p &\text{if }X=\{P\} \\
+1-p&\text{if }X=\{F\}
+\end{cases}
+$$
+
+For exactly two options for $x$ (1 or 0):
+
+$$Pr\{X=x\}=p^x(1-p)^{1-x}$$
+
+Please see [SL Math - Analysis and Approaches 2#Binomial distribution](/g11/mcv4u7/#binomial-distribution) for more information.
+
+A **random variable** is a function that assigns a real number to every item in the sample space. A **discrete random variable** is used if the sample space is discrete. The probability of all events that lead to a possible discrete random variable $x\in\mathbb R$, where $X$ is the function to transform those variables:
+
+$$Pr\{X^{-1}(\{x\})\}$$
+
+Thus the **binomial distribution** for $r$ successes of $n$ total tries, if they are independent, is:
+
+$$Pr\{X=r\}{n\choose r}p^rq^{n-r}$$