Exam-style question
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A fixed number of independent trials each have two outcomes and constant probability of success. Which distribution model is appropriate? Show your working one step at a time.
Model answer
What a good answer should say
- The final answer is a binomial model is appropriate.
- Identify the model as a binomial distribution.
- Check there is a fixed number of trials.
- Check the trials are independent.
This answer is tied to the objective: N1 Understand and use simple discrete probability distributions, excluding calculation of mean and variance of discrete random variables; use the binomial distribution as a model and calculate probabilities using the binomial distribution..
Explanation
Why this works
Use the explanation to connect the worked answer back to N1 Understand and use simple discrete probability distributions, excluding calculation of mean and variance of discrete random variables; use the binomial distribution as a model and calculate probabilities using the binomial distribution..
exam warm-up keeps the canonical answer a binomial model is appropriate 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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