CAIE S2 2015 June — Question 7

Exam BoardCAIE
ModuleS2 (Statistics 2)
Year2015
SessionJune
TopicApproximating the Binomial to the Poisson distribution
TypeState Poisson approximation with justification

7 In a certain lottery, 10500 tickets have been sold altogether and each ticket has a probability of 0.0002 of winning a prize. The random variable \(X\) denotes the number of prize-winning tickets that have been sold.
  1. State, with a justification, an approximating distribution for \(X\).
  2. Use your approximating distribution to find \(\mathrm { P } ( X < 4 )\).
  3. Use your approximating distribution to find the conditional probability that \(X < 4\), given that \(X \geqslant 1\).