Edexcel S2 2002 January — Question 7

Exam BoardEdexcel
ModuleS2 (Statistics 2)
Year2002
SessionJanuary
TopicCumulative distribution functions
TypeContinuous CDF with polynomial pieces

7. A continuous random variable \(X\) has cumulative distribution function \(\mathrm { F } ( x )\) given by $$\mathrm { F } ( x ) = \left\{ \begin{array} { l r } 0 , & x < 0
k x ^ { 2 } + 2 k x , & 0 \leq x \leq 2
8 k , & x > 2 \end{array} \right.$$
  1. Show that \(k = \frac { 1 } { 8 }\).
  2. Find the median of \(X\).
  3. Find the probability density function \(\mathrm { f } ( x )\).
  4. Sketch \(\mathrm { f } ( x )\) for all values of \(x\).
  5. Write down the mode of \(X\).
  6. Find \(\mathrm { E } ( X )\).
  7. Comment on the skewness of this distribution.