Edexcel S2 2008 January — Question 4

Exam BoardEdexcel
ModuleS2 (Statistics 2)
Year2008
SessionJanuary
TopicCumulative distribution functions
TypeContinuous CDF with polynomial pieces

  1. The continuous random variable \(Y\) has cumulative distribution function \(\mathrm { F } ( y )\) given by
$$\mathrm { F } ( y ) = \left\{ \begin{array} { c l } 0 & y < 1
k \left( y ^ { 4 } + y ^ { 2 } - 2 \right) & 1 \leqslant y \leqslant 2
1 & y > 2 \end{array} \right.$$
  1. Show that \(k = \frac { 1 } { 18 }\).
  2. Find \(\mathrm { P } ( Y > 1.5 )\).
  3. Specify fully the probability density function f(y).