Chapter 14 exercises 14.1 7question solution using direct method

1.	Chapter 14 exercises 14.1 7question solution using direct method
Answer» 7. To find out the concentration of SO2\xa0in the air (in parts per million, i.e., ppm), the data was collected for 30 localities in a certain city and is presented below:\tConcentration of SO2\xa0( in ppm)Frequency0.00 – 0.0440.04 – 0.0890.08 – 0.1290.12 – 0.1620.16 – 0.2040.20 – 0.242\tFind the mean concentration of SO2\xa0in the air.Solution:To find out the mean, first find the midpoint of the given frequencies as follows:\tConcentration of SO2\xa0(in ppm)Frequency (fi)Mid-point (xi)fixi0.00-0.0440.020.080.04-0.0890.060.540.08-0.1290.100.900.12-0.1620.140.280.16-0.2040.180.720.20-0.2420.200.40TotalSum fi\xa0= 30\xa0Sum (fixi) = 2.96\tThe formula to find out the mean isMean = x̄ = ∑fixi\xa0/∑fi= 2.96/30= 0.099 ppmTherefore, the mean concentration of SO2\xa0in air is 0.099 ppm.

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