For a sample of 40 cars, a student calculates the correlation coefficient between CO2 _2\,2 emission and CO emission as 0.72. She then discovers that one car's CO2 _2\,2 emission was entered as 1900 g/km when the correct value is 190 g/km.
Describe how this error would appear on a scatter diagram of the data.
Explain why the value 0.72 cannot be trusted.
State what the student should do, and state what she should check before doing it.
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.