While test makers have long been able to turn even the simplest concepts into some seriously heavy lifting, there are some concepts and question types that are statistically more difficult for students than others. In this brief post I’m going to detail some of the question types and concepts that students have the most trouble with.

**Rare Logical Reasoning Questions**

There are certain types of Logical Reasoning questions that appear very rarely, and can require some fairly complex reasoning and elimination. Take a look at this example:

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Although definitely solvable, this is not a question type that you really want to see on test day.

**Data Sufficiency Questions**

Anyone who has studied a significant amount of time for the GMAT already knows this hard lesson very well. Data Sufficiency questions are a pain! The only promising aspect of these questions is that as your familiarity with these questions increases, the ease with which you may solve them grows very quickly. Take a look at the example:

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Solving this question requires not only familiarity with the Data Sufficiency question type, but also intricate knowledge of either number theory and inequalities OR elimination techniques. The correct answer to this question is E (BOTH are NOT sufficient to determine the answer).

**Advanced Set Problems**

Although rare, Venn Diagram or Set problems with *three sets* may appear on the test. These problems regularly prove difficult for students because the knowledge that they test is simply not commonly presented or prioritized.

The two-set formula is fairly easy to remember:

Total = Group1 + Group2 – Both + Neither

But there is a specific formula for *three-set* Venn Diagram problems, which often goes neglected:

Total = Group1 + Group2 + Group3 – (Sum of 2-Group Overlaps) – (n*(All Three) + Neither

The problems that you will face on the GMAT will give you everything that you need in this formula except for *one quantity*, which makes these very easy to solve – IF you know the formula.

This is by no means an exhaustive list; the GMAT is capable of turning even the simplest concepts into devastatingly convoluted quandaries, as you are no doubt well aware of.