CAIE S2 2015 June — Question 2

Exam BoardCAIE
ModuleS2 (Statistics 2)
Year2015
SessionJune
TopicHypothesis test of binomial distributions
TypePerform one-tailed hypothesis test

2 Sami claims that he can read minds. He asks each of 50 people to choose one of the 5 letters A, B, C, D or E. He then tells each person which letter he believes they have chosen. He gets 13 correct. Sami says "This shows that I can read minds, because 13 is more than I would have got right if I were just guessing."
  1. State null and alternative hypotheses for a test of Sami's claim.
  2. Test at the \(10 \%\) significance level whether Sami's claim is justified.