CAIE S2 2020 June — Question 5

Exam BoardCAIE
ModuleS2 (Statistics 2)
Year2020
SessionJune
TopicPoisson Distribution
TypePoisson parameter from given probability

5
  1. The random variable \(X\) has the distribution \(\operatorname { Po } ( \lambda )\).
    1. State the values that \(X\) can take.
      It is given that \(\mathrm { P } ( X = 1 ) = 3 \times \mathrm { P } ( X = 0 )\).
    2. Find \(\lambda\).
    3. Find \(\mathrm { P } ( 4 \leqslant X \leqslant 6 )\).
  2. The random variable \(Y\) has the distribution \(\operatorname { Po } ( \mu )\) where \(\mu\) is large. Using a suitable approximating distribution, it is found that \(\mathrm { P } ( Y < 46 ) = 0.0668\), correct to 4 decimal places. Find \(\mu\).