Pearson Edexcel IAL Mathematics S2.4.4 Critical region

Practise defining a critical region for a test statistic and using tail probabilities to decide whether an observed value is significant.

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The number of cars entering a safari park per 10 -minute period can be modelled, by a Poisson distribution with mean 6

Determine the critical region for the test at the 5\% level of significance.

$J\sim \operatorname{Po}(9)$ $P(J\le 13)=0.9261$ $P(J\le 14)=0.9585$

So the critical region is $J\ge 15$ .

Marking guidance for 4(f):
M1 for writing or using $\operatorname{Po}(9)$ , implied by a correct critical region.
A1 cao. Allow J>14. Do not allow as part of a probability statement.

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S2.4.4 - Critical region question 1