The CO emission x x\,x g/km of each of 30 cars is recorded. For these cars,
∑x=7.5\sum x = 7.5∑x=7.5 and ∑x2=2.118\sum x^2 = 2.118∑x2=2.118
The two largest recorded values are 0.48 g/km and 0.55 g/km, and the smallest is 0.08 g/km.
For this question, a value is defined to be an outlier if it is more than two standard deviations from the mean.
Show that the mean is 0.25 g/km and the standard deviation is 0.09 g/km.
Determine which of the recorded values are classed as outliers.
The two largest values are found to be errors and are removed. Find the mean and the standard deviation of the remaining 28 values.
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.