First a hat tip to CDR Salamander for posting this.
There is a rather interesting test on general politics/sociology/history at this site.
The good CDR got 58 of 60. I managed 51. Not great, a solid B at 85%. Actually, as I haven't been in any kind of non-specialized course work since the mid 1970's, I was reasonably pleased. The site says the average score is about 43 correct (a low C at 71.9%).
Given that the average is around 72%, how many would get below 60%? In other words, how many voters would be unable to pass such a test?
I think I'll ponder that for a while.