Edexcel S3 — Question 6

Exam BoardEdexcel
ModuleS3 (Statistics 3)
TopicChi-squared distribution

6. Data were collected on the number of female puppies born in 200 litters of size 8. It was decided to test whether or not a binomial model with parameters \(n = 8\) and \(p = 0.5\) is a suitable model for these data. The following table shows the observed frequencies and the expected frequencies, to 2 decimal places, obtained in order to carry out this test.
Number of femalesObserved number of littersExpected number of litters
010.78
196.25
22721.88
346\(R\)
449\(S\)
535\(T\)
62621.88
756.25
820.78
  1. Find the values of \(R , S\) and \(T\).
  2. Carry out the test to determine whether or not this binomial model is a suitable one. State your hypotheses clearly and use a \(5 \%\) level of significance. An alternative test might have involved estimating \(p\) rather than assuming \(p = 0.5\).
  3. Explain how this would have affected the test.