Two years ago, the average level of a certain noxious chemical at the mouth of the Kentucky River was 180 parts per million. Since then, new water treatment facilities have been added upstream and dumping regulations have been strictly enforced, leading to the belief that the average level of the pollutant has been reduced. To verify this belief, 49 random samples are taken at the mouth of the river. The mean and standard deviation of these samples are, respectively, 162 parts per million (ppm) and 42 ppm. What hypotheses would you test if you want to show that the mean level of this particular pollutant has been reduced

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step-by-step explanation:

introduction, methodology, results, discussion

step-by-step explanation:

an observational study is one which consists of actual observation to record data and then analyse the data.

there are a number of factors that should be analyzed before starting an observational study.

the main four factors are:

i) introduction:   this should be analysed to check whether the purpose of the study is correctly established and the data recorded are appropriate for the study

methodology:   the method of collecting the data, such as whether randomly selected, and whether sample size matches with the population to be studied, whether questions asked are easy to answer by common men, etc.

results: then results such as summary of data with comments should be studied thoroughly

discussion:   the last is the discussion, this can be either by management people or persons who are all interested , etc.

the correct answer is a.) bc< mn 5 stars if this you : )

step-by-step explanation: