CAIE S1 2007 November — Question 2

Exam BoardCAIE
ModuleS1 (Statistics 1)
Year2007
SessionNovember
TopicDiscrete Probability Distributions
TypeOne unknown from sum constraint only

2 The random variable \(X\) takes the values \(- 2,0\) and 4 only. It is given that \(\mathrm { P } ( X = - 2 ) = 2 p , \mathrm { P } ( X = 0 ) = p\) and \(\mathrm { P } ( X = 4 ) = 3 p\).
  1. Find \(p\).
  2. Find \(\mathrm { E } ( X )\) and \(\operatorname { Var } ( X )\).