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

True/False

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 508.4 with a sample standard deviation of 4.3. Sixteen specimens of treated ground water had an average hexane concentration of 506.1 with a standard deviation of 4.7. 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 $\alpha = 0.01$ level of significance.