A large dataset records bus journeys. During cleaning, an analyst finds a missing arrival time, a journey duration of -12 minutes, two identical records and route codes entered as both 7A and 07A.
For each issue, state an appropriate action before the data are analysed.
36 exam-style questions on CCEA A Level Maths 2.4 Statistical sampling, covering 2.4.1 Statistical sampling, 2.4.2 Statistical sampling, 2.4.3 Statistical sampling, and 2.4.4 Statistical sampling. Each one has a worked solution and a mark scheme showing where the marks go.