Edexcel FS1 2020 June — Question 6

Exam BoardEdexcel
ModuleFS1 (Further Statistics 1)
Year2020
SessionJune
TopicProbability Generating Functions
TypeSolve for parameters using PGF coefficients

  1. A discrete random variable \(X\) has probability generating function given by
$$\mathrm { G } _ { X } ( t ) = \frac { 1 } { 64 } \left( a + b t ^ { 2 } \right) ^ { 2 }$$ where \(a\) and \(b\) are positive constants.
  1. Write down the value of \(\mathrm { P } ( X = 3 )\) Given that \(\mathrm { P } ( X = 4 ) = \frac { 25 } { 64 }\)
    1. find \(\mathrm { P } ( X = 2 )\)
    2. find \(\mathrm { E } ( X )\) The random variable \(Y = 3 X + 2\)
  2. Find the probability generating function of \(Y\)