AQA S2 2007 June — Question 6

Exam BoardAQA
ModuleS2 (Statistics 2)
Year2007
SessionJune
TopicDiscrete Probability Distributions
TypeDerive or identify E(aX+b) or Var(aX+b) formulas

6 The continuous random variable \(X\) has the probability density function given by $$f ( x ) = \left\{ \begin{array} { c c } 3 x ^ { 2 } & 0 < x \leqslant 1
0 & \text { otherwise } \end{array} \right.$$
  1. Determine:
    1. \(\mathrm { E } \left( \frac { 1 } { X } \right)\);
      (3 marks)
    2. \(\operatorname { Var } \left( \frac { 1 } { X } \right)\).
  2. Hence, or otherwise, find the mean and the variance of \(\left( \frac { 5 + 2 X } { X } \right)\).