CAIE S1 2024 March — Question 5

Exam BoardCAIE
ModuleS1 (Statistics 1)
Year2024
SessionMarch
TopicDiscrete Probability Distributions
TypeVerify probability from given formula

5 Anil is taking part in a tournament. In each game in this tournament, players are awarded 2 points for a win, 1 point for a draw and 0 points for a loss. For each of Anil's games, the probabilities that he will win, draw or lose are \(0.5,0.3\) and 0.2 respectively. The results of the games are all independent of each other. The random variable \(X\) is the total number of points that Anil scores in his first 3 games in the tournament.
  1. Show that \(\mathrm { P } ( X = 2 ) = 0.114\).
  2. Complete the probability distribution table for \(X\).
    \(x\)0123456
    \(\mathrm { P } ( \mathrm { X } = \mathrm { x } )\)0.1140.2070.2850.125
  3. Find the value of \(\operatorname { Var } ( X )\).