CAIE S2 2005 November — Question 2

Exam BoardCAIE
ModuleS2 (Statistics 2)
Year2005
SessionNovember
TopicHypothesis test of binomial distributions
TypeExplain Type I or II error

2 A manufacturer claims that \(20 \%\) of sugar-coated chocolate beans are red. George suspects that this percentage is actually less than \(20 \%\) and so he takes a random sample of 15 chocolate beans and performs a hypothesis test with the null hypothesis \(p = 0.2\) against the alternative hypothesis \(p < 0.2\). He decides to reject the null hypothesis in favour of the alternative hypothesis if there are 0 or 1 red beans in the sample.
  1. With reference to this situation, explain what is meant by a Type I error.
  2. Find the probability of a Type I error in George's test.