Commit c84c106

@@ -59,6 +59,36 @@ WHERE HoursWorked < 100;
 | 165 | Honou    | Morris    | 6/9/1993   | $6.70   | 53          |
 ```
 
-Chapter 15:
+Chapter 15: Artificial Intelligence
 
-Chapter 16:
+> 4. In the following neural network, which event or events cause node N3 to fire?
+
+```plaintext
+1 --1---|
+        V
+      (N1 2) ------2----|
+        A               |
+        |               |
+2 --2---|               V
+                      (N3 3) ----->
+3 --1---|               A
+        V               |
+      (N2 2) ------2----|
+        A
+        |
+4 --2---|
+```
+
+N3 will fire when the following events occurr:
+
+| 1 | 2 | 3 | 4 |
+| - | - | - | - |
+| X | X | X | X |
+| X | X | - | X |
+| - | X | X | X |
+| - | X | - | X |
+
+* X: is On
+* -: is Off
+
+Chapter 16: Computer Graphics and Entertainment: Movies, Games and Virtual Communities