In a random sample of 30 Local Authorities, 12 had an increase of more than 2 percentage points in the proportion working mainly at or from home between 2001 and 2011. In an independent random sample of 80 Local Authorities, 28 had such an increase.
Calculate the two sample proportions.
Use each sample separately to estimate the number, out of 348, with such an increase.
Calculate the estimate obtained by combining the two samples.
Explain why none of the three estimates should be presented as an exact population count.
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.