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

In your Build Configuration, make sure you check your library to be exported in Order and Export. See