RI Sampling Tutorial Q8

RI Sampling Tutorial Q8

7 marks
Tutorial

A random variable \(X\) has probability distribution given by

\(\mathrm{P}\left( X=x \right)=\left\{ \begin{matrix} kx\left( 6-x \right),x=1,\ 2,\ 3,\ 4,\ 5 \\ 0,\,\,\,\,\,\,\,\,\,\,\mathrm{otherwise} \end{matrix} \right.\)

  1. Show that \(k=\frac{1}{35}\)[1]
  2. Find the mean and variance of \(X\).[3]

\(40\) independent observations of \(X\) are taken.

  1. Find the probability that the sum of the \(40\) observations of \(X\) exceeds \(110\).[3]

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Answer:(ii) \(\mathrm{E}(X) = 3\), \(\mathrm{Var}(X) = 1.6\); (iii) \(0.894\)

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