8/10, and, as mentioned in the explanation on the second blog post, I did feel like I was giving ridiculously wide ranges for some of them, turns out I wasn't ridiculous enough - as one commenter points out, a more interesting exercise might be to do the same but with 50% ranges - then the simple solution of "make an estimate and put 3 orders of magnitude each side" doesn't help.
Also, the length of the coastline of the Pacific, which is one of the ones I got right is, as HonoreDB and several commentors on the blog post have pointed out, undefined - it depends what length ruler you use.
So you think its important to be able to estimate how well you are estimating something? Here is a fun test that has been given to plenty of other people.
I highly recommend you take the test before reading any more.
http://www.codinghorror.com/blog/2006/06/how-good-an-estimator-are-you.html
The discussion of this test at the blog it is quoted in is quite interesting, but I recommend you read it after taking the test. Similarly, one might anticipate there will be interesting discussion here on the test and whether it means what we want it to mean and so on.
My great apologies if this has been posted before. I did my bast with google trying to find any trace of this test, but if this has already been done, please let me know and ideally, let me know how I can remove my own duplicate post.
PS: The Southern California meetup 19 Dec 2010 was fantastic, thanks so much JenniferRM for setting it up. This post on my part is an indirect result of what we discussed and a fun game we played while we were there.