Edexcel S2 — Question 6

Exam BoardEdexcel
ModuleS2 (Statistics 2)
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TopicContinuous Probability Distributions and Random Variables

6. A continuous random variable \(X\) has probability density function \(\mathrm { f } ( x )\) where $$f ( x ) = \begin{cases} k \left( 4 x - x ^ { 3 } \right) , & 0 \leqslant x \leqslant 2 \\ 0 , & \text { otherwise } \end{cases}$$ where \(k\) is a positive integer.
  1. Show that \(k = \frac { 1 } { 4 }\). Find
  2. \(\mathrm { E } ( X )\),
  3. the mode of \(X\),
  4. the median of \(X\).
  5. Comment on the skewness of the distribution.
  6. Sketch f(x).

6. A continuous random variable $X$ has probability density function $\mathrm { f } ( x )$ where

$$f ( x ) = \begin{cases} k \left( 4 x - x ^ { 3 } \right) , & 0 \leqslant x \leqslant 2 \\ 0 , & \text { otherwise } \end{cases}$$

where $k$ is a positive integer.\\
(a) Show that $k = \frac { 1 } { 4 }$.

Find\\
(b) $\mathrm { E } ( X )$,\\
(c) the mode of $X$,\\
(d) the median of $X$.\\
(e) Comment on the skewness of the distribution.\\
(f) Sketch f(x).\\

\hfill \mbox{\textit{Edexcel S2  Q6}}