Exam-style question
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Use a checking method for this problem: For independent events A and B with P(A) = 0.5 and P(B) = 0.5, find P(A and B). State the final answer and verify it against the information in the question.
Model answer
What a good answer should say
- A valid checked answer is 0.25.
- The method is: Use the multiplication rule because the events are independent.
- Multiply P(A) by P(B).
- 0.5 x 0.5 = 0.25.
This answer is tied to the objective: L3 Interpret measures of central tendency and variation, extending to standard deviation; calculate standard deviation, including from summary statistics..
Explanation
Why this works
Use the explanation to connect the worked answer back to L3 Interpret measures of central tendency and variation, extending to standard deviation; calculate standard deviation, including from summary statistics..
calculator check keeps the canonical answer 0.25 fixed before the model answer is written, so the worked solution and final answer agree.
Maths method check
- Topic focus: Statistics.
- Question style: exam_style.
- Reasoning demand: recall.
- Check the operation, notation, units, and final answer form against the question before moving on.
Common mistake
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