Attachment D .gov

If you have ten samples, then 10 X 0.9 is 9. Find sample number 9. This sample is the 90th percentile. If you only have five samples, the 90th percentile is the average value of the two highest lead samples. (Add your two highest values and divide by 2.) A 90th percentile value higher than 0.015 mg/L for lead and 1.30 mg/L for copper is an ... ................
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