The average CPC for "insurance" keyword, for example is $20, then how much percentage of this CPC will be paid by adsense to us per click?
Well it's kind of hard to answer this question, because only google knows the answer, plus they never tell us and never will how much you will get paid.
It all depends on your site's traffic, and the quality of the content. We're not google, we can't determine any type of money you'll earn