Edexcel S2 2008 January — Question 6

Exam BoardEdexcel
ModuleS2 (Statistics 2)
Year2008
SessionJanuary
TopicApproximating Binomial to Normal Distribution
TypeCompare approximation methods

6. The probability that a sunflower plant grows over 1.5 metres high is 0.25 . A random sample of 40 sunflower plants is taken and each sunflower plant is measured and its height recorded.
  1. Find the probability that the number of sunflower plants over 1.5 m high is between 8 and 13 (inclusive) using
    1. a Poisson approximation,
    2. a Normal approximation.
  2. Write down which of the approximations used in part (a) is the most accurate estimate of the probability. You must give a reason for your answer.