Question about the "hard" OG 12th Edition Problems

If you want to judge how well you are doing on the difficult questions, where you need improvement, and what steps that might take to improve, then we get exceedingly little useful information about those important things simply from percentages and overall right/wrong ratios. The real learning for the GMAT happens at the detail level. For example, if there are questions for which you don't understand the explanation, or you don't feel confident that you will remember the explanation and be able to avoid the same mistake next time, these would be great individual posts on GC. If you see any patterns of mistakes, that also would be an excellent thing to discuss in a post. Make it your goal to milk every difficult question, all of them but especially the ones you got wrong, for every ounce of learning you could possibly squeeze out of them --- this may well involve posting each one on this forum (or finding where they are already posted) and reading what various experts have to say about them.

I would also recommend perusing our free blog ----
https://magoosh.com/gmat/
Some of the articles will cover basic stuff, but I believe, if you search through the whole blog, you will find several tips for handing tricky questions of all categories. Magoosh also has solutions for all the math & SC questions posted on Youtube --- search there.
https://www.youtube.com/user/MagooshGMAT

Also, here's a free DS question:
https://gmat.magoosh.com/questions/984
and here's a free CR question:
https://gmat.magoosh.com/questions/3117
For each one of those, after your submit your answer, the following page will have a video explanation. Each one of our 800+ GMAT questions has its own video explanation, for accelerated learning.

I hope all this helps.

Mike

To add to what Mike said, OG questions do not reflect the actual test very well. Most of them are on the easier side in OG. There are few questions that I would call 'tough'. If you are at Q50/51, you won't make mistakes in the OG questions. If you are getting some of them wrong, it means there is some way to go (depending on the score you want). Also, OG is good for giving practice questions - the solutions it gives may not be optimum. If you are trying to learn from OG solutions, you may be short changing your preparation. Look for solutions here on the forum or ask your tutor for better explanations. Also, try to get to the root of the concept rather than focusing on 'how to solve this question'.