What are you drinking? Environmental Protection Agency standards require that the amount of lead in drinking water be less than 15 micrograms per liter. Twelve samples of water from a particular source have the following concentrations, in units of micrograms per liter. Assume the population standard deviation is o =5. If appropriate, perform a hypothesis test to determine whether you can conclude that the mean concentration of lead meets the EPA standards. Use the a = 0.01 level of significance and the P-value method with the TI-84 calculator. 11.6 14.2 11.8 14.9 15.9 9.8 13.5 8.6 12.3 17.7 9.8 15.8 Send data to Excel