CAIE S1 2022 March — Question 1

Exam BoardCAIE
ModuleS1 (Statistics 1)
Year2022
SessionMarch
TopicDiscrete Probability Distributions
TypeConstruct probability distribution from scenario

1 A fair red spinner has edges numbered \(1,2,2,3\). A fair blue spinner has edges numbered \(- 3 , - 2 , - 1 , - 1\). Each spinner is spun once and the number on the edge on which each spinner lands is noted. The random variable \(X\) denotes the sum of the resulting two numbers.
  1. Draw up the probability distribution table for \(X\).
  2. Given that \(\mathrm { E } ( X ) = 0.25\), find the value of \(\operatorname { Var } ( X )\).