Hi I was wondering if I could get some help on how December 28, 2016 By Essaypros Hi I was wondering if I could get some help on how to figure out the rate ratios, rate difference per 1000 PY? I’m trying to understand the formula. We Deliver Top Quality On Time As Promised! Ready to get started? Just click the button to be directed to a secure page so you can enter the details of your paper.