The masses, x x\,x kg, of 40 cars have mean 1420 kg and standard deviation 180 kg. The masses are coded using
y=x−100020\displaystyle y = \frac{x - 1000}{20}y=20x−1000
Find the mean and the standard deviation of the coded values.
The median of the coded values is 20.5. Find the median mass.
Explain why the standard deviation of the coded values is smaller than 180.
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.