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Find the values for $p$, $q$ and $r$.
Mathematics 9709 · AS & A Level · Linear combinations of random variables
Linear combinations of random variables — practice question
The discrete random variable $X$ is given this probability distribution:
$x = -3, 0, 2, 4$ with probabilities $P(X = x) = p, q, r, 0.4$. It is also given that $\text{E}(X) = 2.3$ and $\mathrm{Var}(X) = 3.01$.
Worked solution & mark scheme
This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: “A correct unsimplified probability equation (for example, one combining $p$, $q$ and $r$)” …
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