To find the probability of Outcome Y given that Outcome 2 occurs, we use the formula for conditional probability:
\[ P(A | B) = \frac{n(A \text{ and } B)}{n(B)} \]
In this case:
- A is Outcome Y
- B is Outcome 2
To find \( n(B) \), you need the total number of occurrences for Outcome 2. From the table, Outcome 2 has:
- Outcome X: 9 occurrences
- Outcome Y: 4 occurrences
So, the total occurrences for Outcome 2 is:
\[ n(B) = 9 + 4 = 13 \]
Therefore, the number you would use in the denominator of your fraction when calculating \( P(Y | \text{Outcome 2}) \) is 13.