Edexcel S2 2014 January — Question 6

Exam BoardEdexcel
ModuleS2 (Statistics 2)
Year2014
SessionJanuary
TopicCumulative distribution functions
TypePDF to CDF derivation

  1. The continuous random variable \(X\) has probability density function given by
$$f ( x ) = \left\{ \begin{array} { c c } k ( x + 1 ) ^ { 2 } & - 1 \leqslant x \leqslant 1
k ( 6 - 2 x ) & 1 < x \leqslant 3
0 & \text { otherwise } \end{array} \right.$$ where \(k\) is a positive constant.
  1. Sketch the graph of \(\mathrm { f } ( x )\).
  2. Show that the value of \(k\) is \(\frac { 3 } { 20 }\)
  3. Define fully the cumulative distribution function \(\mathrm { F } ( x )\).
  4. Find the median of \(X\), giving your answer to 3 significant figures.