A recent study was conducted to determine the concentration of lead in drinking water across various states. 25

water samples from the state of Washington were tested; the mean lead concentration was found to be 0.15%

. This compares to 32

water samples in the state of Minnesota where the mean was reported to be 0.21%

. The data was calculated to be significant at the 0.0001

level. Determine the meaning of this significance level.