(a)[3]
Calculate the probability that a randomly chosen shopper spends between $85$ and $100$ minutes in the shopping centre.
(b)[3]
$88\%$ of shoppers spend more than $t$ minutes in the shopping centre. Determine the value of $t$.
Mathematics 9709 · AS & A Level · The normal distribution
The normal distribution — practice question
The times spent by shoppers in a large shopping centre are normally distributed, with mean $96$ minutes and standard deviation $18$ minutes.
Worked solution & mark scheme
This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Standardisation written correctly as $P\left(\frac{85-96}{18}<Z<\frac{100-96}{18}\right)$” …
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