A sixth-form college has 72 students in Year 12 and 63 students in Year 13. The principal proposes selecting 20 students from Year 12 and 10 students from Year 13, at random within each year group.
State the sampling technique proposed.
Show that the proposed sample is not proportional to the year-group sizes.
Explain one consequence of this lack of proportionality.
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.