The Environmental Protection Agency sets limits on the maximum allowable concentration of certain chemicals in drinking water. For the substance PCB, the limit was set at 5 ppm (parts per million). The PCB level is unsafe if it is greater than 5 ppm. A random sample of 36 water specimens from the same well results in a mean PCB concentration of 5.2 ppm with standard deviation of 0.6 ppm. Does the data substantiate that the water is unsafe?