2024 EJC P2 Q7

2024 EJC P2 Q7

6 marks
Prelims

A random variable \(X\) has the probability distribution given in the following table.

\(x\)\(1\)\(2\)\(3\)\(4\)
\(\mathrm{P}(X = x)\)\(0.4\)\(0.3\)\(0.2\)\(0.1\)
  1. Find \(\mathrm{Var}\left( X \right)\) and show that \(\mathrm{Var}\left( 3X-2 \right)=39.96\).[3]
  2. The mean of \(40\) independent observations of \(X\) is denoted by \(M\). Find an approximate value for \(\mathrm{P}\left( M>3 \right)\).[3]

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Answer:(a) \({4.44}\) (b) \({0.115}\) (\(3\) sofa)

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