There are 12 professors in total. Now that you're aware of this we need to find how many professors are <51 (if the professor is exactly 51, it won't count). The professors ages that this applies to is {39,37,48,33,35,34}. That is 6 professors out of our 12 total. This is 6/12 or 1/2 which directly calculates to 50%. :D
