To find $n(A \cap B)$, we use the formula for the union of two sets:

$n(A \cup B) = n(A) + n(B) - n(A \cap B)$

We are given the following values:

• $n(A) = 110$
• $n(B) = 105$
• $n(A \cup B) = 195$

Now, substitute these values into the formula:

$195 = 110 + 105 - n(A \cap B)$

Simplify the equation:

$195 = 215 - n(A \cap B)$

Solve for $n(A \cap B)$:

$n(A \cap B) = 215 - 195 = 20$

Thus, $n(A \cap B) = 20$.

Would you like further explanation or have any other questions?

Here are 5 related questions:

1. If $n(A \cup B) = 250$, $n(A) = 150$, and $n(A \cap B) = 50$, what is $n(B)$?
2. How would you find $n(A \cup B \cup C)$ if you had three sets involved?
3. If $n(A \cup B) = n(A) + n(B)$, what can you infer about $A$ and $B$?
4. If $A$ and $B$ are mutually exclusive, what is $n(A \cap B)$?
5. How does the inclusion-exclusion principle apply when dealing with more than two sets?

Tip: Always visualize sets with Venn diagrams when working with set operations for a clearer understanding of their relationships.