Ugh, 2 days ago. I'm sorry for the delay - we've been dealing with various news that came out of the recent GMAC conference, so the forums have been neglected.
Let us know whether you did already take the test / whether you still need help.
Concentrating on doing first 10-15 questions right giving them more time than later questions.I know even this strategy is wrong.But I am not sure of any other way
You're right that this strategy is wrong - the earlier questions aren't worth more. The overall balance of your timing is really important - as you found out, going too quickly can be just as much of a problem as going too slowly.
Here's an article about time management:
http://www.manhattangmat.com/blog/index ... anagement/If you haven't taken your test yet or if you plan to re-take, then read that and start doing what it says. It takes about how to learn to spend the right amount of time on each question type and also how to manage your time throughout the entire section.
Needless to say, some of the hard problems in SC,CR were seen earlier hence they went right.
If you take any practice tests on which you see repeated questions, don't automatically get them right! Even more important, don't do them fast - you'd never be able to have that advantage on the real test.
Anytime you see a problem that you remember (and this means: I know the answer or I'm pretty sure I remember the answer, not just "hmm, this looks vaguely familiar..."), immediately look at the timer and make yourself sit there for the full length of time for that question type. This way, you don't artificially give yourself more time than you should have. Second, think about whether you got this problem right the last time. If you did, get it right again this time. If you didn't, get it wrong again. If you *completely honestly* think that you would get it right this time around if it were a new question (even though you got it wrong last time) because you've studied that area and improved, then get it right this time.