Mathematics 9709 · AS & A Level · Linear combinations of random variables

Linear combinations of random variables — practice question

The random variables $X$ and $Y$ are independent, with distributions $N(44, 16)$ and $N(30, 9)$ respectively.
(main)[5]

Find the value of $P(X - Y < 15)$.

Worked solution & mark scheme

This 5-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Hence, $X-Y \sim N(44-30,\,\ldots)=N(14,\,\ldots)$” …

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