Elena downloads the records of 200 cars from the AQA Large Data Set. She finds that one car's CO emission is recorded as 45 g/km, and that three cars have no CO emission recorded at all.
Explain why the value of 45 g/km should be treated as an error.
State what Elena should do with the three records that have no CO emission, and state the number of values she should then use to calculate the mean.
244 exam-style questions on AQA A Level Maths 2.2 L: Data presentation and interpretation, covering 2.2.1 Single-variable data diagrams, 2.2.2 Scatter diagrams and correlation, 2.2.3 Central tendency, variation and standard deviation, 2.2.4 Outliers and cleaning data, and 2.2 L: Data presentation and interpretation. Each one has a worked solution and a mark scheme showing where the marks go.