Mathematics 9709 · AS & A Level · Continuous random variables

Continuous random variables — practice question

The probability density function of the random variable $X$ is given by $f(x) = \begin{cases} \dfrac{kx^2}{a^2}, & 0 \leq x \leq a, \\ 0, & \text{otherwise}, \end{cases}$ where $k$ and $a$ are positive constants.
(a)[3]

Show that, indeed, $k = \dfrac{3}{a}$.

(b)[3]

Find the value of $a$ when $\text{E}(X) = 1$.

(c)[3]

Find the median value of $X$.

Worked solution & mark scheme

This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: Begin with $\frac{k}{a^2}\int_0^a x^2\,dx=1$

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