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Find the value of $P(X_1 > 3X_2)$.
Mathematics 9709 · AS & A Level · Linear combinations of random variables
Linear combinations of random variables — practice question
The random variable $X$ follows $N(31.2, 10.4^2)$. Two independent draws from $X$, labelled $X_1$ and $X_2$, are taken.
Worked solution & mark scheme
This 5-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Find $E(X_1-3X_2)=31.2-3\times31.2=-62.4$ (or an equivalent form).” …
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