Study the table below, which shows the monthly mean concentration of PM2.5\text{PM}_{2.5}PM2.5 particulate matter (μg/m3\mu\text{g/m}^3μg/m3) recorded at an urban monitoring station.
| Month | PM2.5\text{PM}_{2.5}PM2.5 concentration (μg/m3\mu\text{g/m}^3μg/m3) |
|---|---|
| January | 18.4 |
| February | 16.8 |
| March | 15.2 |
| April | 12.1 |
| May | 9.8 |
| June | 8.5 |
| July | 7.9 |
| August | 8.2 |
| September | 10.4 |
| October | 13.6 |
| November | 16.1 |
| December | 17.5 |
Calculate the mean monthly PM2.5\text{PM}_{2.5}PM2.5 concentration for this station to two decimal places (2dp).
Show your working.
