A call centre lists its 9600 calls in time order. Staffing changes every two hours. An analyst selects every 120th call after choosing a random starting call from the first 120 calls.
State the sample size.
Explain why the sample may give a misleading result if the number of calls handled in each two-hour period is close to 120.
Suggest a different method that avoids this possible problem.
36 exam-style questions on WJEC A Level Maths 2.1 Statistical Sampling, covering 2.1.1 Statistical Sampling, 2.1.2 Statistical Sampling, 2.1.3 Statistical Sampling, 2.1.4 Statistical Sampling, and 2.1 Statistical Sampling. Each one has a worked solution and a mark scheme showing where the marks go.