The GMAT Quant generally throws up a few problems that designed to act as speed-breakers during the course of the 75-minute Quantitative section. Not surprisingly, these questions are what are usually referred to as the Roman Numeral problems — information followed by III statements, with the question asking you identify the statements that could be true, must be true or is true. Depending upon the the question stem — could be or must be — you need to follow a specific approach to nail these questions without wasting much time. But one still has to proceed with the knowledge that these problems will take a tad longer to solve than the others since the equivalent of since almost three questions is built into one question.
One of the reasons why the GMAT is my favourite test of all is that it is so well defined in terms of the skills tested and consistently so. One of the things that is absolutely essential to remember on the GMAT Problem Solving (PS) is that the test-setters do not want you to do donkey work with respect to calculation. The leading companies in the world are not paying thousands of dollars to hire graduates from premier b-schools to do what a calculator can do!