(a)[3]
Construct the probability distribution table for $X$, with probabilities expressed as numerical fractions.
(b)[3]
Find the value of $\mathrm{Var}(X)$.
Mathematics 9709 · AS & A Level · Discrete random variables
Discrete random variables — practice question
The random variable $X$ may assume the values $-2, -1, 0, 2, 3$. It is stated that $P(X = x) = k(x^2 + 2)$, where $k$ is a positive constant.
Worked solution & mark scheme
This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Finds $k=\frac{1}{28}$ by using the fact that the probabilities sum to 1” …
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