Mathematics 9709 · AS & A Level · The Poisson distribution

The Poisson distribution — practice question

At Restaurant Bijoux, 13% of customers judged the food to be ‘poor’, 22% judged it to be ‘satisfactory’ and 65% judged it to be ‘good’. A random sample of 12 customers who had a meal at Restaurant Bijoux was selected.
(i)[3]

Find the probability that more than $2$ and fewer than $12$ of them rated the food as ‘good’.

(ii)[3]

At another time, a random sample of $n$ customers who had a meal at the restaurant was selected. Find the smallest value of $n$ for which the probability that at least $1$ person will rate the food as ‘poor’ exceeds $0.95$.

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