Well, most active and passive basses when you don't use EQ are very similar. After all, the front end of your head is basically an active preamp! An active bass merely moves part of that EQ circuit into the bass where it more convenient to adjust while you are playing.
In the Common Application, it says that the Personal Essay should be at least 250 words, and attached on a separate sheet (presumably, if you're submitting it online, you attach a one-page file).
Obviously, the longer your essay, the greater the number of paragraphs it will contain. As others have suggested, a very rough average for a paragraph is 100 words. So, a 500-word essay would, by this reckoning, have approximately five paragraphs. Much also depends on your topic.