Edexcel FS2 2024 June — Question 5

Exam BoardEdexcel
ModuleFS2 (Further Statistics 2)
Year2024
SessionJune
TopicCumulative distribution functions
TypeCDF with additional constraints

  1. A continuous random variable \(X\) has probability density function
$$f ( x ) = \left\{ \begin{array} { c l } a x ^ { - 2 } - b x ^ { - 3 } & 2 \leqslant x < \infty
0 & \text { otherwise } \end{array} \right.$$ where \(a\) and \(b\) are constants. Given that \(\mathrm { P } ( X \leqslant 4 ) = \frac { 3 } { 8 }\)
  1. use algebraic integration to show that \(a = 3\) Show your working clearly.
  2. Find the exact value of the median of \(X\)