Mathematics 9709 · AS & A Level · Continuous random variables

Continuous random variables — practice question

The probability density function, $f$, for the random variable $X$ is defined by $f(x)=\begin{cases}k(1+\cos x), & 0 \le x \le \pi,\\ 0, & \text{otherwise},\end{cases}$ where $k$ denotes a constant.
(a)[3]

Show that $k=\frac{1}{\pi}$.

(b)[3]

Confirm that the median of $X$ is between $0.83$ and $0.84$.

(c)[4]

Find the exact value of $\mathrm{E}(X)$.

Worked solution & mark scheme

This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: Try $\int_0^{\pi}k(1+\cos x)\,dx=1$.

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