Changes in Problems Used
The vast majority of the math questions in the 12th edition Official Guide appear verbatim but in a different order, than in the 13th edition. Here’s a list of questions in the OG 12 that have not been reused in the OG 13:
2, 5, 18, 42, 46, 47, 48, 51, 52, 53, 55, 56, 59, 73, 74, 81, 86, 87, 88, 89, 91, 107, 111, 117, 148, 151, 163, 178, 179, 180, 181, 182, 183*, 184, 185, 186, 187, 188, 189, 190, 191, 197, 199, 203, 220, 227.
13, 16, 17, 18, 19*, 22, 26, 27, 28, 32*, 33, 36, 41, 42, 45, 46, 48, 53, 59, 62, 66, 71, 72, 75, 76, 79, 82, 90, 91, 94, 98, 110, 141, 148, 164*, 170.
*indicates a question that has not be used verbatim, but which seems to have served as the inspiration for a new question in the OG 13.
New GMAT Math Trends
The questions removed cover a wide range of topics, as do the new questions added, so it’s really impossible to say much that would encapsulate all the changes.
I notice two trends. First, there seems to be increased attention to some slightly more sophisticated algebra, including recognition and use of the difference of two squares pattern:
The second seems to be increased attention to number properties — already a huge topic. In particular, there is some new focus on decimals and patterns involving decimals.
Just so everyone is clear: the printed copy of new book, the OG 13, does not have IR problems. The printed OG 13 has a short 11 page overview the IR question format. Interestingly, their section on Graphics Interpretation includes a couple new types of charts not mentioned on the original GMAC website posting information on this question. These include
1) bubble charts — this is a kind of a scatterplot which, instead of points or dots, has circles of varying radii — the radii of the circles indicate a third variable independent of the x- and y-axis. The Wikipedia article has a few good images: http://en.wikipedia.org/wiki/Bubble_chart
2) flow charts — these charts show steps in a process, and what to do given different decisions at different points in the process. Here are a couple humor flow charts, one on learning how to cook (http://xkcd.com/854/), one giving a humorous generalization of tech support (http://xkcd.com/627/) and one simply on understanding flow charts (http://xkcd.com/518/)
3) organization chart — these show the levels of a hierarchy: who’s on the same level as who, and who’s above/below who. Here’s the organization chart for the US government, in case you were curious: http://www.netage.com/economics/gov/Gov-chart-top.html
Again, there are no practice IR questions in the print version of the 13th edition of the Official Guide. Each copy of the 13th edition comes with a code that gives the user access to GMAC’s companion website with 50 IR questions.
As always, what’s the best way to prepare for this? With Magoosh, you will get all the content & strategy you need in video form, 800+ practice questions, each with its own video explanation, and responsive support for any questions you have.