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Find the probability that the mean from a random sample of 36 values of $X$ is less than $405$.
Mathematics 9709 · AS & A Level · Sampling and estimation
Sampling and estimation — practice question
A random variable $X$ follows the distribution $N(410, 400)$.
Worked solution & mark scheme
This 3-mark question has a full step-by-step worked solution and mark scheme. One marking point: “By standardising, obtain $\frac{405-410}{20}= -1.5$ (or an equivalent form such as $\frac{14580-14760}{\sqrt{14400}}$).” …
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