A researcher is interested in the amount of a contaminant found in the Cuyahoga River. This chemical has been found to be the cause of tumors in fish and is believed to be cancer causing to people as well. She takes 41 samples from the river and finds a mean concentration of 4.841 per liter with a standard deviation of 1.600 per liter. Construct a 90% confidence interval for the true population mean of concentration in the river. If the National Institute of Health feels that a concentration of 6.0 is problematic, should you be concerned?