WAEC 2021 Mathematics · Question 7
A fair die is tossed twice what is the probability of get a sum of at least 10.
Options
- A.
- B.
- C.
- D.
Answer: D.
Explanation written with AI and checked against the answer key
Analyze the question: A fair die is tossed twice, and we want the probability that the sum is at least 10, meaning a sum of 10, 11 or 12. Concept: Probability = (number of favourable outcomes) ÷ (total number of outcomes). Tossing a die twice gives 6 × 6 = 36 equally likely outcomes. Solution: Sum = 10: (4,6), (5,5), (6,4) → 3 outcomes Sum = 11: (5,6), (6,5) → 2 outcomes Sum = 12: (6,6) → 1 outcome Favourable outcomes = 3 + 2 + 1 = 6 P(sum ≥ 10) = 6/36 = 1/6 Tip: For two-dice questions, list the outcomes by each possible sum (as above) so you don't miss any. Also simplify your fraction at the end, since 6/36 reduces to 1/6, which is how it appears in the options. Be careful not to confuse "at least 10" (10 or more) with "exactly 10", which would give 3/36 = 1/12.AI can make mistakes. Report anything that looks wrong.
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