Mathematics 9709 · AS & A Level · Continuous random variables

Continuous random variables — practice question

Let $X$ be a random variable with probability density function defined by $f(x)=\begin{cases}k(2x^2-x^3), & 0\leq x\leq 2,\\0, & \text{otherwise}.\end{cases}$ The median of $X$ is written as $m$.
(a)[3]

Show that $k=\frac{3}{4}$ by using the fact that the total probability is $1$.

(b(i))[1]

State the value of $\mathrm{P}(X\leq m)$.

(b(ii))[5]

Hence, find $\mathrm{P}(\mathrm{E}(X)\leq X\leq m)$.

Worked solution & mark scheme

This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: The required setup is $k\int_0^2(2x^2-x^3)\,dx=1$.

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