The 50-50-90 rule: Anytime you have a 50-50 chance of getting something right, there's a 90% probability you'll get it wrong.
Q:

Dear 100 Hour Board,

Graduation is coming up, and that got me thinking. Each college has a different color of tassel and collar that they wear. How was each color assigned to each college? Was it totally random, or did they assign pink to the college of fine arts on purpose because they thought the guys in that college were the least likely to protest about it?

- Neapolitan

A: Dear Neapolitan,

As far as I can tell from earlier research (Board Question #14789), the color assignments are random.

- Katya