7 At a certain hospital it was found that the probability that a patient did not arrive for an appointment was 0.2 . The hospital carries out some publicity in the hope that this probability will be reduced. They wish to test whether the publicity has worked.
- It is suggested that the first 30 appointments on a Monday should be used for the test. Give a reason why this is not an appropriate sample.
A suitable sample of 30 appointments is selected and the number of patients that do not arrive is noted. This figure is used to carry out a test at the 5\% significance level. - Explain why the test is one-tail and state suitable null and alternative hypotheses.
- State what is meant by a Type I error in this context.
- Use the binomial distribution to find the critical region, and find the probability of a Type I error.
- In fact 3 patients out of the 30 do not arrive. State the conclusion of the test, explaining your answer.