The concentration of hexane (a common solvent) was measured in units of micrograms per liter for a simple random sample of nineteen specimens of untreated ground water taken near a municipal Landfill. The sample mean was 289.2 with a sample standard deviation of 6.3. Twenty-two Specimens of treated ground water had an average hexane concentration of 285.3 with a standard Deviation of 7.6. It is reasonable to assume that both samples come from populations that are approximately normal. Can you Conclude that the mean hexane concentration is less in treated water than in untreated water? Use the α = Level of significance.

Question

Quizplus · Accepted Answer

The sample mean of the untreated water is greater than the sample mean of the treated water, and the sample standard deviation of the untreated water is less than the sample standard deviation of the treated water. This suggests that the mean hexane concentration is less in treated water than in untreated water.

The Concentration of Hexane (A Common Solvent) Was Measured in Units