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We are often told that the discrete random variable in the question can be modelled by a Poisson distribution.
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If not, phrases like 'constant average rate' are the giveaway sign.
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Binomial questions don't seem to come up a lot in S2, but they are sometimes thrown in amongst Poisson questions.
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There must be a fixed number of independent trials for the binomial distribution to be applicable. The trials must also have 2 outcomes, success or failure, and the probability of success must be constant for each trial.
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In S2, the standard normal distribution is mainly used to calculate confidence intervals and carry out hypothesis tests. Be careful here though, as depending on the information given in the question, we may have to use the Student's t-distribution instead.
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The examiner often tells us that the discrete random variable in the question can be modelled by a Poisson distribution.
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If not, look for phrases like 'constant average rate'.
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Binomial questions don't come up a lot as they are mainly covered in S1, but they are sometimes thrown in amongst Poisson questions.
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There must be a fixed number of independent trials for the binomial distribution to be applicable. The trials must have 2 outcomes, success or failure, and the probability of success must be constant for each trial.
•
In S2, the standard normal distribution is mainly used to calculate confidence intervals and carry out hypothesis tests. Be careful here though, as depending on the information given in the question, we often have to use the Student's t-distribution instead.