CAIE S2 2013 June — Question 1

Exam BoardCAIE
ModuleS2 (Statistics 2)
Year2013
SessionJune
TopicApproximating the Binomial to the Poisson distribution
TypeState Poisson approximation with justification

1 It is known that \(1.2 \%\) of rods made by a certain machine are bent. The random variable \(X\) denotes the number of bent rods in a random sample of 400 rods.
  1. State the distribution of \(X\).
  2. State, with a reason, a suitable approximate distribution for \(X\).
  3. Use your approximate distribution to find the probability that the sample will include more than 2 bent rods.