This is a exam practice Qn. I am unsure of how to do it. I am not trying to submit your answer as mine.
An environmental company was commissioned to study the air quality by measuring the amounts of dioxin (ng/m3 ) in the air at an industrial area on the days immediately following a chemical plant leakage. Dioxin includes a group of chemicals produced from burning and some types of manufacturing. Dioxin readings were taken at 38 randomly selected locations within the industrial area. The summarised results of the readings are as shown in Table Q3-1 and Table Q3-2. Assume that the sample standard deviation is a reliable estimate for the population standard deviation of the Dioxin readings.
(i) Calculate and state the 95% confidence interval for the population mean Dioxin readings?