Two standard dice are thrown simultaneously. What is the probability that the sum of the two upper faces equals 8?

Difficulty: Easy

Correct Answer: 5/36

Explanation:


Introduction / Context:
Rolling two fair six-sided dice yields 36 equally likely ordered pairs. We want the chance that the sum is exactly 8.



Given Data / Assumptions:

  • Die outcomes are 1–6.
  • Sample space size = 6 × 6 = 36.
  • Sum target = 8.


Concept / Approach:
Enumerate the pairs whose coordinates sum to 8 and divide by 36.



Step-by-Step Solution:
Favorable pairs: (2,6), (3,5), (4,4), (5,3), (6,2) → 5 outcomes.Probability = 5 / 36.



Verification / Alternative check:
Check neighboring sums: sums of 7 have 6 outcomes (symmetric peak), sums of 8 have 5, consistent with standard sum distribution.



Why Other Options Are Wrong:
2/9 ≈ 8/36 (too large); 1/6 = 6/36 (wrong count); “Data Inadequate” is inappropriate since the model is standard.



Common Pitfalls:
Forgetting that ordered pairs (3,5) and (5,3) are distinct outcomes.



Final Answer:
5/36

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