A city council wants to estimate the proportion of cars driven in the city centre that have a CO emission above 0.4 g/km. The council can borrow roadside measuring equipment for one week.
Identify the population and the sampling units for this investigation.
Describe a method the council could use to obtain a sample of 500 cars, and state the sampling method your description uses.
Give one reason why the council's estimate may be biased, and state how the method could be changed to reduce that bias.
28 exam-style questions on AQA A Level Maths 2.1 K: Statistical sampling, covering 2.1.1 Populations, samples and sampling techniques. Each one has a worked solution and a mark scheme showing where the marks go.