In one shop, customers come independently and at random, with a steady average rate of $23.4$ per hour.
(a)[3]
Determine the probability that, in a randomly selected $1$-minute interval, at least $2$ customers arrive.
(b(i))[2]
State an appropriate approximating distribution for $X$ and specify the parameter value(s).
(b(ii))[3]
Use the approximating distribution to calculate $\mathrm{P}(20 < X < 30)$.
Worked solution & mark scheme
This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Calculate $\lambda = \frac{23.4}{60} = 0.39$” …
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