Yup! It's a Google secret. Thanks Anya <a href="http://www.padanagloves.com" title="Garden Gloves">Garden Gloves</a> Manufacturer
The lowest cost for an adsense AD that google can accept it from an advertiser is 10 cents per click, however we as publishers sometimes (well many times) have only 1 cent per click, what does that mean It means the ratio is at least 10:1 , imagine how much google makes money from us !!!!!!!
30-60% is what i have heard. Depending on the quality of the websites along with the average clicks a day go into how much your going to make.