Mathematics 9709 · AS & A Level · The Poisson distribution

The Poisson distribution — practice question

A survey carried out by a large supermarket found that $35\%$ of its customers buy online.
(i)[3]

Six customers are selected at random. Find the probability that more than three of them buy online.

(ii)[3]

In a random sample of $n$ customers, the probability that at least one of them shops online is above $0.95$. Determine the smallest possible value of $n$.

(iii)[5]

In a random sample of $100$ customers, use an appropriate approximating distribution to find the probability that more than $39$ shop online.

Worked solution & mark scheme

This 11-mark question has a full step-by-step worked solution and mark scheme. One marking point: Binomial sum $\sum_{r=4}^6 \binom{6}{r}0.35^r0.65^{6-r}$

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