13 Two random samples of 12 NOX emissions (in \(\mathrm { g } / \mathrm { km }\) ) were taken from the Large Data Set.
One sample was taken from the 2002 data and the other sample from the 2016 data.
The sample data are shown below:
| \multirow{2}{*}{2002} | 0.031 | 0.019 | 0.091 | 0.025 | 0.030 | 0.061 |
| 0.047 | 0.029 | 0.059 | 0.363 | 0.330 | 0.376 |
| \multirow{2}{*}{2016} | 0.005 | 0.047 | 0.053 | 0.063 | 0.026 | 0.013 |
| 0.058 | 0.012 | 0.010 | 0.010 | 0.008 | 0.008 |
The mean and standard deviation of the 2002 sample data are 0.122 and 0.137 respectively.
13
- Find the mean and standard deviation of the 2016 sample data giving your answers correct to three decimal places.
13 - Siti claims these samples show that, on average, the NOX emissions across all makes of car in all areas of the UK have fallen by over 75\% between 2002 and 2016.
13
- Show how Siti's claim of 'over 75\%' has been obtained.
13
- (ii) Using your knowledge of the Large Data Set, make two comments on the validity of Siti's claim.
Comment 1
\section*{Comment 2}