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 context:
- \( A \) is "Outcome Y"
- \( B \) is "Outcome 2"
The denominator \( n(B) \) is the total number of occurrences of Outcome 2. From the table, we can see that the total occurrences for Outcome 2 (across all events) is 13.
Thus, the number you would use in the denominator of your fraction is 13.