Commons Math - could not find class org.apache.commons

I have downloaded the binary Zip from here. I extracted the zip to a folder. Then I right clicked on `libs` folder in Eclipse. I Imported the *.jar file to the `libs` folder, and then I right clicked on it and `added to path`. I added ``` import org.apache.commons.math3.stat.descriptive.DescriptiveStatistics; ``` to my java file, and i am adding values to ``` DescriptiveStatistics rStandardDeviation = new DescriptiveStatistics(); ``` and after that I run the math part by: ``` double bMean = bStandardDeviation.getMean(); double rStd = rStandardDeviation.getStandardDeviation(); ``` No errors on compile, clean, or build. When I attempt to run the app on my phone i get: ``` Could not find class 'org.apache.commons.math3.stat.descriptive.DescriptiveStatistics', referenced from method com.example.mydemo.MainActivity.<init> ``` Any ideas anyone what is going wrong? Thank you