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Determine the chance that a value of $X$, chosen at random, falls between $25$ and $30$.
Mathematics 9709 · AS & A Level · Continuous random variables
Continuous random variables — practice question
It is stated that $X \sim N(28.3,\,4.5)$.
Worked solution & mark scheme
This 3-mark question has a full step-by-step worked solution and mark scheme. One marking point: “At least one value standardised correctly, e.g. $z_1 = \frac{30-28.3}{\sqrt{4.5}}$ or $z_2 = \frac{25-28.3}{\sqrt{4.5}}$, with the sign correct; no continuity correction” …
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