Two fair dice are thrown. What is the probability that the sum of the numbers is ?
Answer and explanation
Correct answer: A. 1/18
- Step 1: When two fair six-sided dice are thrown, the total number of equally likely outcomes in the sample space is .
- Step 2: Identify the ordered pairs whose sum equals : (1, 2), (2, 1), giving favorable combinations.
- Step 3: The probability is the ratio of favorable outcomes to total outcomes: .
Answer
1/18.
Why not the others: 1/6 assumes a uniform distribution over all possible sums; 1/36 assumes only a single outcome yields the required dice sum; 1/12 is the probability of obtaining a sum of or ().
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