Discrete Random Variables (DRV)

Discrete Random Variables (DRV)

IB AA SL: core and optional content

Core: the distribution table, E(X), and Var(X) by the binomial model np(1−p) (SL route solution). Optional: the general E(X²) method for Var(X) used in the default solution.

\(3\) dice are thrown simultaneously. Let \(X\) be the random variable of number of sixes obtained. Construct the probability distribution table for \(X\) and show that \(X\) is a discrete random variable. Find \(\mathrm{E}\left( X \right)\) and \(\mathrm{Var}\left( X \right)\).

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Answer:\(\text{E}\hspace{0.1em}\left( X \right)=\frac{1}{2}\); \(\text{Var}\hspace{0.1em}\left( X \right)=\frac{5}{12}\)

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