Question 7:
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:
Find the mean concentration of SO2 in the air.
Answer:
To find the class marks for each interval, the following relation is used.
Class size of this data = 0.04
Taking 0.14 as assumed mean (a), di, ui, fiui are calculated as follows.
From the table, we obtain
Therefore, mean concentration of SO2 in the air is 0.099 ppm.
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