OCR S3 2010 January — Question 4

Exam BoardOCR
ModuleS3 (Statistics 3)
Year2010
SessionJanuary
TopicCumulative distribution functions
TypeCDF of transformed variable

4 The continuous random variable \(V\) has (cumulative) distribution function given by $$\mathrm { F } ( v ) = \begin{cases} 0 & v < 1
1 - \frac { 8 } { ( 1 + v ) ^ { 3 } } & v \geqslant 1 \end{cases}$$ The random variable \(Y\) is given by \(Y = \frac { 1 } { 1 + V }\).
  1. Show that the (cumulative) distribution function of \(Y\) is \(8 y ^ { 3 }\), over an interval to be stated, and find the probability density function of \(Y\).
  2. Find \(\mathrm { E } \left( \frac { 1 } { Y ^ { 2 } } \right)\).