Pretty much all of my students have, at some point or another, seen a really easy question on the GMAT, and had a mild panic attack as a result. We all know that the GMAT test is adaptive; if, say, question #25 seems really easy, doesn’t that mean that the test-taker is doing really really badly? No, of course not.
Well, okay… maybe. If you’re doing really badly, you probably will see some really easy questions, particularly on the math section of the GMAT. But there are other possible explanations, and perhaps you've heard them before; based on my experience as a GMAT tutor, these explanations still don't prevent students from freaking out a little bit.
First of all, there are plenty of experimental questions on the GMAT. You might be kicking some serious butt, and then a complete softball comes your way. Is it a sign that you weren't really kicking butt? Probably not. You might just have received a little unscored nugget. Answer the question as if it counts, and then put it out of your head.
I'm also convinced that the GMAT algorithms group questions by topic, and the test actually accounts for your performance on each topic. You might have done wonderfully on the first, say, 12 questions on the GMAT, but then you miss your first geometry question. Perhaps the test recalls that you screwed up on geometry, and then gives you an easy geometry question next time. This is just speculation on my part, but I think it's possible that seemingly easy GMAT questions might come at you when you've displayed weakness on a particular topic--even if you haven't, in general, shown yourself to be a weak test-taker.
Most importantly, you should never worry about the difficulty level of the questions. If a GMAT question seems easy, read it really, really carefully--it might not be as easy as you think, or you might be missing something crucial in the question. And even if it is easy, why the hell would you want to waste your energy worrying about it? Get the question right, and don't worry about your GMAT score until the end of the test.
This might seem obvious to you, and this post is obviously just a little bit of nagging. But it's funny how many people apparently need to be reminded that they shouldn't waste their time thinking about the algorithm and their score during the GMAT.