AQA S2 2010 January — Question 8

Exam BoardAQA
ModuleS2 (Statistics 2)
Year2010
SessionJanuary
TopicContinuous Probability Distributions and Random Variables
TypeCalculate and compare mean, median, mode

8 The continuous random variable \(X\) has probability density function given by $$\mathrm { f } ( x ) = \left\{ \begin{array} { c c } \frac { 1 } { 2 } \left( x ^ { 2 } + 1 \right) & 0 \leqslant x \leqslant 1
( x - 2 ) ^ { 2 } & 1 \leqslant x \leqslant 2
0 & \text { otherwise } \end{array} \right.$$
  1. Sketch the graph of f.
  2. Calculate \(\mathrm { P } ( X \leqslant 1 )\).
  3. Show that \(\mathrm { E } \left( X ^ { 2 } \right) = \frac { 4 } { 5 }\).
    1. Given that \(\mathrm { E } ( X ) = \frac { 19 } { 24 }\) and that \(\operatorname { Var } ( X ) = \frac { 499 } { k }\), find the numerical value of \(k\).
    2. Find \(\mathrm { E } \left( 5 X ^ { 2 } + 24 X - 3 \right)\).
    3. Find \(\operatorname { Var } ( 12 X - 5 )\).