To find out the concentration of SO2 in the air (in parts per million, i.e., ppm), the data was collected for 30 localities in a certain city and is presented below:
Concentration of SO2 (in ppm) |
0.00-0.04 |
0.04-0.08 |
0.08-012 |
0.12-0.16 |
0.16-0.20 |
0.20-0.24 |
Frequencey |
4 |
9 |
9 |
2 |
4 |
2 |
Find the mean concentration of SO2 in the air.