So I didn’t *win* Monday Math Madness. For those of you not in the know, the blog WildAboutMath is having a rotating math problem contest with another website, and I put my hat in the ring. And I got the answer right. Sadly, the random number generator did not love me (click link for a few different solutions).

This week’s problem was:

A popular blog has just three categories: brilliant, insightful, and clever. Every blog post belongs to exactly one of the three categories and the category for each post is selected at random. What is the probability of reading at least one post from each category if a reader reads exactly five posts?

After solving it, I tried thinking of natural extensions. Clearly, one is: “if you have p posts and n tags: what is the probability that a reader reads at least one post from each category if a reader reads exactly p posts?” Or one could think about the more difficult question, where the frequency of each tag is different (not equal chance of stumbling across each post).

My submitted solution after the fold. You can see how hard it is to explain math clearly in an email.

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