The bulk of the questions in OG12
and OG13 are the same. The main difference is:
1) Integrated Reasoning section in OG13, it gives you online access to 50 IR questions.
2) Quantitative: 81 of the 452 problems are new(the total number of Quant problems are the same)
3) Verbal: 77 of the 455 are new(the total number of Verbal questions is the same)
Essentially, they have dropped 158 problems in Quant and Verbal and replaced it with new ones.
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