CAIE S1 2023 November — Question 1

Exam BoardCAIE
ModuleS1 (Statistics 1)
Year2023
SessionNovember
TopicDiscrete Probability Distributions
TypeSimple algebraic expression for P(X=x)

1 Becky sometimes works in an office and sometimes works at home. The random variable \(X\) denotes the number of days that she works at home in any given week. It is given that $$\mathrm { P } ( X = x ) = k x ( x + 1 )$$ where \(k\) is a constant and \(x = 1,2,3\) or 4 only.
  1. Draw up the probability distribution table for \(X\), giving the probabilities as numerical fractions.
  2. Find \(\mathrm { E } ( X )\) and \(\operatorname { Var } ( X )\).