OCR MEI S2 2006 June — Question 1

Exam BoardOCR MEI
ModuleS2 (Statistics 2)
Year2006
SessionJune
TopicApproximating the Binomial to the Poisson distribution
TypeState conditions for Poisson approximation

1 A low-cost airline charges for breakfasts on its early morning flights. On average, \(10 \%\) of passengers order breakfast.
  1. Find the probability that, out of 8 randomly selected passengers, exactly 1 orders breakfast.
  2. Use a suitable Poisson approximating distribution to find the probability that the number of breakfasts ordered by 30 randomly selected passengers is
    (A) exactly 6,
    (B) at least 8 .
  3. State the conditions under which the use of a Poisson distribution is appropriate as an approximation to a binomial distribution.
  4. The aircraft carries 120 passengers and the flight is always full. Find the mean \(\mu\) and variance \(\sigma ^ { 2 }\) of a Normal approximating distribution suitable for modelling the total number of passengers on the flight who order breakfast.
  5. Use your Normal approximating distribution to calculate the probability that more than 15 breakfasts are ordered on a particular flight.
  6. The airline wishes to be at least \(99 \%\) certain that the plane will have sufficient breakfasts for all passengers who order them. Find the minimum number of breakfasts which should be carried on each flight.