Question

To find out the concentration of `SO_(2)` 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 `SO_(2)` in the air.

Answer 1

We have (assumed mean) a=0.10 (class width) h=0.04,
(total observation. ) `N=30 and sum f_(i)u_(i)=-1`
By step deviation method,
`"Mean"=a+hxx(1)/(N)xxsumf_(i)u_(i)`
`=0.10+0.04xx(1)/(30)xx(-1)`
`=0.10-(0.04)/(30)`
`=0.010-0.001=0.009` ppm