Read the first sentence--the first freakin' sentence--of this article, and see what's wrong. There's no math there. The answer given--is the wrong freakin' answer. Perhaps the reporter misinterpreted the problem, but as it's written, it's wrong wrong wrong. There is a correct answer here, and 40% isn't it. In fact, several minutes of instruction in combinatorics would give an answer well under half of what was reported.
Ugh! This was such a great book, and I read it back in the 80s. Sad that it's still so true.