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Find the probability that the mean of a random sample of 36 values of $X$ is below $405$.
Mathematics 9709 · AS & A Level · Sampling and estimation
Sampling and estimation — practice question
The 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: “Standardise to obtain $\frac{405-410}{20/6}=-1.5$ and use the normal distribution ($\sqrt{36}$ required).” …
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