1. **State the problem:** We want to find the conditional probability that neither die shows a 2 given that the sum of the two dice is greater than 8.
2. **Recall the formula for conditional probability:**
$$P(A|B) = \frac{P(A \cap B)}{P(B)}$$
where $A$ is the event "neither die is a 2" and $B$ is the event "sum > 8".
3. **Calculate $P(B)$, the probability that the sum is greater than 8:**
Possible sums greater than 8 are 9, 10, 11, and 12.
- Sum = 9: (3,6), (4,5), (5,4), (6,3) → 4 outcomes
- Sum = 10: (4,6), (5,5), (6,4) → 3 outcomes
- Sum = 11: (5,6), (6,5) → 2 outcomes
- Sum = 12: (6,6) → 1 outcome
Total outcomes with sum > 8 = 4 + 3 + 2 + 1 = 10
Total possible outcomes when rolling two dice = $6 \times 6 = 36$
So,
$$P(B) = \frac{10}{36} = \frac{5}{18}$$
4. **Calculate $P(A \cap B)$, the probability that neither die is 2 and the sum is greater than 8:**
We list all outcomes with sum > 8 and exclude those with a 2:
- Sum = 9: (3,6), (4,5), (5,4), (6,3) — none have 2 → 4 outcomes
- Sum = 10: (4,6), (5,5), (6,4) — none have 2 → 3 outcomes
- Sum = 11: (5,6), (6,5) — none have 2 → 2 outcomes
- Sum = 12: (6,6) — no 2 → 1 outcome
Total valid outcomes = 4 + 3 + 2 + 1 = 10
So,
$$P(A \cap B) = \frac{10}{36} = \frac{5}{18}$$
5. **Calculate the conditional probability:**
$$P(A|B) = \frac{P(A \cap B)}{P(B)} = \frac{\frac{5}{18}}{\frac{5}{18}} = 1$$
**Final answer:**
$$\boxed{1}$$
This means that if the sum is greater than 8, it is certain that neither die is a 2.
Conditional Probability Dice 9923Ec
Step-by-step solutions with LaTeX - clean, fast, and student-friendly.