Improving you speed comes from learning how to address different question types. Many times people can overpower GMAT questions with brute force. That means, when you give them 5-10 minutes they could figure out the right or wrong answer just by going through all the different ways they THINK they might get to the right answer. This will not work on test day. In fact, you will get crushed on test day if you even spend more than 3 minutes on ANY question.
My advice is to concetrate more on HOW to solve questions the correct way the first time/every time. This will mean that you should work harder on your fundamentals, and also work very hard on reviewing practice problems to make sure that if you ever see one of them again, you will be able to solve it the right way the first time. The best way to learn to do this is to implement an
error log into your studying.
Once you start feeling a little more comfortable, start testing yourself under timed conditions and never go over 2-3 minutes on ANY problem. Learn how to guess correctly, and make educated guess, so that timing doesn't kill you. Once you are done with those problems, go back, figure out why you were unable to solve in the right amount of time, and learn from your mistake and take notes in your
error log.
Just remember, every question on the GMAT has been created to be solved in under 3 minutes. So even the absolut toughest GMAT questions can be solved in the right amount of time.
Over time, you will pick up short cuts, and learn pattern recognition, and these will all help with speed.
Good luck!
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