CAIE S2 2019 November — Question 5

Exam BoardCAIE
ModuleS2 (Statistics 2)
Year2019
SessionNovember
TopicApproximating the Binomial to the Poisson distribution
TypeFind parameter from Poisson probabilities

5
  1. The random variable \(X\) has the distribution \(\mathrm { B } ( 300,0.01 )\). Use a Poisson approximation to find \(\mathrm { P } ( 2 < X < 6 )\).
  2. The random variable \(Y\) has the distribution \(\mathrm { Po } ( \lambda )\), and \(\mathrm { P } ( Y = 0 ) = \mathrm { P } ( Y = 2 )\). Find \(\lambda\).
  3. The random variable \(Z\) has the distribution \(\mathrm { Po } ( 5.2 )\) and it is given that \(\mathrm { P } ( Z = n ) < \mathrm { P } ( Z = n + 1 )\).
    (a) Write down an inequality in \(n\).
    (b) Hence or otherwise find the largest possible value of \(n\).