To find the probability of Outcome Y given that Outcome 2 occurs, you would use the total number of occurrences of Outcome 2 as the denominator in the probability formula \( P(A|B) = \frac{n(A \text{ and } B)}{n(B)} \).
First, let's summarize the counts from the provided data for Outcome 2:
- For Outcome X, Outcome 2 occurs 9 times.
- For Outcome Y, Outcome 2 occurs 4 times.
Now, the total for Outcome 2 is calculated by adding the counts from both outcomes:
Total for Outcome 2 = 9 (Outcome X) + 4 (Outcome Y) = 13
Thus, \( n(B) \), the total number of occurrences for Outcome 2, would be 13.
So, the number you would use in the denominator of your fraction when calculating \( P(A|B) \) is:
A. 13