Question

Given below is the frequency distribution table regarding the concentration of sulphur dioxide in the air in parts per million of a certain city for 30 days.

Conc. of SO2	0.00-0.04	0.04-0.08	0.08-0.12	0.12-0.16	0.16-0.20	0.20-0.24
No. days:	4	8	9	2	4	3

 

Find the probability of concentration of sulphur dioxide in the interval 0.12-0.16 on any of these days.

Answer 1

The total number of trials is 30.

Remember the empirical or experimental or observed frequency approach to probability.

If n be the total number of trials of an experiment and A is an event associated to it such that A happens in m-trials. Then the empirical probability of happening of event A is denoted by P (A)  and is given by

`P (A) = m/n`

Let A₁ be the event that the concentration of sulphur dioxide in a day is 0.12-0.16 parts per million.

The number of times A₁ happens is 2.

Therefore, we have

` P(A_1) = 2/30`

             `=1/15`