The CO2 _2\,2 emissions, x x\,x g/km, of 20 cars are coded using
y=x−15010\displaystyle y = \frac{x - 150}{10}y=10x−150
For the 20 coded values, the mean is 2.4 and the standard deviation is 0.6.
Find the mean of the CO2 _2\,2 emissions.
Find the standard deviation of the CO2 _2\,2 emissions.
State the effect on the standard deviation of subtracting 150 from every value.
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.