It depends on the civic tests and their "difficulty".
Also you are putting words into my mouth. On any issue of race, people like to put words into other people's mouth- all sides do it. It's probably the first thing they do and really hinders having a civil discussion on the matter. In fact, I did not say those who failed the civic tests were stupid. Granted, my word choice does gets me in trouble sometimes, but I have never used "stupid" to describe a group. That's probably far from the truth. Ignorant is a better word because I do believe blacks have the same ability as whites, asians, hispanics, etc. There is just a difference in level of formal education.
I do not condone Cosby's methods- you're not going to help coming across as like you said "senile". But I do respect and understand why he feels the way he does when you look at things such as drop out rates, college enrollment rates, imprisonment rates, pregnancy rates, social attitudes, etc. and the factors causing them.
Seriously, if you want me to put a number to "decent percentage", I'm sorry I can't because again I said it would be an interesting hypothetical. But I'll give you this:
http://nces.ed.gov/fastfacts/display.asp?id=16This is only for ages 16-24, which does not include people older and younger who dropped out. However these stats are at least encouraging, even though the gap has closed only a little in the 1990s and 2000s compared to previous decades, it is not increasing. What's even more interesting is the statistics for Hispanics.
And I have no right to be a racist if you're implying that I am. I will NOT say I have no prejudices, as no one is prejudice free. But being Asian, raised by New England white parents, in a relatively asian-less Southern state (unless you go up to northern VA and DC area), I can say I've had my fair share of race stereotyping and identity issues as a child.
Some of the kindest people and easiest to talk I know are blacks, and when you are willing to go back to work at McDonalds for each year for 5 summers, ignoring the craptacular job and hours, but feel like being called someone's "boo" and other pet names, and staying in contact with your co-workers is better than starting all over again for a couple of bucks more an hour... then I can say I am not someone who is racist. I am not saying I have experienced and can completely empathize with people different than myself, but I can say I have taken the time to listen to opposing views, listen to other's plights, and ask people different from myself WHY and HOW they feel on sensitive issues such as race. Maybe not as many as Barack Obama or Hilary Clinton...
As leet_muffin pointed out, this is assuming that people actually go out to vote... which is unrealistic. But when you think about this election and the black voter turn out, it makes you wonder are we seeing a light at the end of the tunnel?