A random sample of 50 bus journeys gives a mean delay of 4.2 minutes. One recorded delay is missing.
State one action the researcher should take before analysing the individual journey data.
A researcher concludes that the mean delay of every bus journey is exactly 4.2 minutes. Explain why this conclusion is not justified.
36 exam-style questions on OCR A Level Maths 2.1 Statistical Sampling, covering 2.1.1 Population and sample, 2.1.2 Informal inferences from samples, 2.1.3 Sampling techniques, 2.1.4 Selecting or critiquing sampling techniques, and 2.1 Statistical Sampling. Each one has a worked solution and a mark scheme showing where the marks go.