diff --git a/UNB/Year 4/Semester 2/CS3873/CS2024-01-22.md b/UNB/Year 4/Semester 2/CS3873/CS2024-01-22.md
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--- a/UNB/Year 4/Semester 2/CS3873/CS2024-01-22.md	
+++ b/UNB/Year 4/Semester 2/CS3873/CS2024-01-22.md	
@@ -1,3 +1,8 @@
 Lecture Topic:
-
-Packet Switching: Congestion
+# Packet Switching
+## Congestion
+A relevant example is air plane ticket overbooking. If an air plane has a capacity of 100 seats, and the probability of of a passenger showing up to their flight is 80%, then you can overbook ticket sales due to the probability of passengers not showing up
+- If 110 tickets are sold, the probability of more than 100 passengers is 0.0058%
+- If 115 tickets are sold, the probability goes up to 1.94%
+- If 120 tickets are sold, the probability is 15.17%
+- If 130 tickets are sold, the probability is 78.12%
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