CAIE S2 2024 June — Question 6

Exam BoardCAIE
ModuleS2 (Statistics 2)
Year2024
SessionJune
TopicHypothesis test of a normal distribution

6 The numbers of green sweets in 200 randomly chosen packets of Frutos are summarised in the table.
Number of green sweets0123\(> 3\)
Number of packets325097210
  1. Calculate an unbiased estimate for the population mean of the number of green sweets in a packet of Frutos, and show that an unbiased estimate of the population variance is 0.783 correct to 3 significant figures.
    The manufacturers of Frutos claim that the mean number of green sweets in a packet is 1.65 .
    Anji believes that the true value of the mean, \(\mu\), is less than 1.65 . She uses the results from the 200 randomly chosen packets to test the manufacturers’ claim.
  2. State suitable null and alternative hypotheses for the test.
    \includegraphics[max width=\textwidth, alt={}, center]{7c078a14-98f9-4292-ae76-a2642238176f-08_2714_37_143_2008}
  3. Show that the result of Anji's test is significant at the \(5 \%\) level but not at the \(1 \%\) level.
  4. It is given that Anji made a Type I error. Explain how this shows that the significance level that Anji used in her test was not \(1 \%\).