Funny you mentioned that. I actually am in the same boat... I can nail the OG questions relatively fast (1-1.5min) but when I take MGMAT cat's I score in the 44-47 range on quant. Yet on GMATPrep cat I score 48/49 on the quant. So makes me a little uneasy also.

Hi guys

I've experienced quite the same thing... Actually OG PS questions reach a tough level in a 1 out of 5 ratio... By solving questions from 200 to 230 you skipped some 35/40 that are listed before.
However OG questions looked to me slightly easier than those in the GMATprep simulation.

Good luck with your practice.

This is a common theme - the Official Guide questions do not seem to be difficult enough compared to unofficial questions. When I am manning the Veritas helpline people often call to ask about the difficulty level of the Veritas Prep Simulator Test because the questions are more difficult than those in the OG and on the GMATPrep test as well (Veritas Students have access to the helpline and over a dozen CATs and you can access a free Veritas practice test at https://www.veritasprep.com/free-gmat-practice-test/).

This is one reason why people choose to work with supplemental materials as well as the Official Guide. Here are my thoughts:

1) The Official Guide does verbal in a style that almost perfectly matches that of the official test. Verbal questions are all about the smallest word choices and details and great editing, the OG does this very well.

2) However, the OG is NOT diverse enough with things like the more unusual types of critical reasoning questions (OG is heavy on strengthen and weaken) and there are too few really dense reading comp passages -- so supplemental materials are important for verbal.

3) On the Quant portion there are two different types of difficulty:

• A) Upfront conceptual scary difficulty -- this is what you are talking about as lacking in the OG and that is true. There are fewer questions in the OG that just frighten you when you see them. This is a reason to get supplemental material, because the actual GMAT has more difficulty than the OG.
  
  B) Subtle difficulty - this is something that the GMAT does very well. This is where a question is setup in such a way as to send people to the wrong answer without them even knowing it. There is a phenomenon with official GMAT questions, especially Data Sufficiency where the person who has missed the question actually has more confidence in his answer than the person who got it right! This type of difficulty is done well in the OG - and I must say that it is done well in the Veritas quant books as well. Have you tried the Data Sufficiency in the OG? You may find those more difficult.

Kenji is right, by the way, you should really go through all the OG questions as you may find that you have difficulty somewhere along the way, and if not, then you are looking pretty good.

Oh and one more thing, don't underestimate the fact that doing questions on the computer versus in a book makes them tougher as well. A book is just less threatening.

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Thanks kenji and David, useful responses.

I did an additional 30 problems in PS without much trouble. I started the DS problems yesterday, and found them to be more difficult and better practice.