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pemdas

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Everything posted by pemdas

  1. are you applying for PhD? the verbal is a bit low, I wished it were 153 min. but you can always balance with solid toefl close to 110 or exceeding so PhD or MBA?
  2. actually being doubtful even at the verge of your perfection is a good sign. It only implies you are perceptive to traps if you were strained for time by the end of exam, provided you double checked the marked answers, this could be attributed to wrong strategy selected. I think some one has asked me about such issues in test but for different exam - GMAT. Here what was my response in PM to that individual. Question: Hay Hi...I have been following your posts from long time in BTG. I need one help, where can I get some info on ball-parking, backward solving methods for Quant. I really need it. Though I am a 42-45 Quant scorer but I need to improve my speed. comment: ball-parking and back-ward solving are the strategy types used in GMAt quant section when the questions are challenging. Answer: ball-parking is just approximation in solution process and back-ward solving is the combination of plug-in values/substitution. Some questions may be very cumbersome to come with the final answer, and if you have decent fundas and practiced math for a long time, by first approaching the question it should be clear whether you can solve it the way you selected or this will take forever. If the latter is a case at hand (forever, difficult subtle way solution is needed) you should start looking for substitution immediately to save time and come with at least some meaningful answer rather wasting minutes on the obdurately formulated problem.
  3. who's one? I am not American
  4. I would retake it and stay focused more on the weakness areas. Usually for some one scoring in the range of 159/160 + the weaknesses could be ignoring tricks in the straightforwardly set questions like number of factors in 27 (simple example to ease calculations) --> 3^3 --> (3+1) --> 4 factors --> 27,9,3,1 / Mark answer as 4 <BUM!> trick by ETS factors not specified +ve/-ve, hence 4*2=8 factors including -ve factors too, should have marked 8. such straightforwardly set questions check our limitations re certain issues including math of GRE. Next, look for the areas (by trying to remember a bit the domain tested) which took most time (meaning not 10 minutes, but above 2 mins) from you in test. Coordinate geometry for example, what was in there some silly distance formula application which you didn't remember always and considered useless but could help you decipher the VIC type of question related to the topic. Some word problem involving speeds, ratios?
  5. some one called me , there's difference between (-5)^2 and -5^2. As Alf correctly explained unless the parentheses are present we follow the arithmetical operations' order (parentheses, exponents, multiplication, division, addition, subtraction) from the left to the right usually reminder for those whose regular alphabetical reading habit is from the right to the left (e.g. Hebrew, Arabic)
  6. little easy level math comparable to those from elementary school's (2-3) grades suggests that you should submit the first test score totaling up to 300 overall score, whereas your second test resulted in lower 298. Your AWA is in the same ranking interval 5.5-6.00 so it makes less sense to submit the second test's score. If the heck is AWA score then reread ETS scoring table again.
  7. not 12th but 20th - it was paper based test and I will receive score report not earlier than Nov.19
  8. Hi guys, first time poster here. I ran into some confusion while using Sid Thatte's GRE/GMAT math book. There are two probability practice problems which Mr. Thatte seems to solve with different approaches. They are as follows: Question 1 (dice-sum problem). If you roll two dice, what's the probability that the sum of the two numbers you get will be 6? 1-5, 2-4, 3-3 and vice versa 5-1, 4-2, 3-3. Total 6 options out of 6*6=36 possibilities. So the chance is p=6/36 or 1/6 Question 2 (list-product problem). If you have two lists of numbers, list A being 1-3-5 and list B being 2-5-6, you select one number from each list, what is the probability that the product of the two numbers will be odd? In the list A we have all odd numbers and the list A contains only one odd number (5). The product of odd numbers is always odd, so we have only three options (5*1, 5*3, 5*5) out of possible 3*3=9 possibilities and the chance is p=3/9 or 1/3 My confusion is in the way the book calculates the denominator (aka the total # of outcomes) of each probability. In the dice-sum problem, they counted the total # of outcomes as the number of dice roll arrangements, not as the total # of unique sums. In the list-product problem, they did the exact opposite and counted the total # of outcomes as the number of unique products that were possible, not the total # of arrangements of number choices. i.e., in the dice-sum problem, the book counts 36 total possible outcomes, which is 6*6, or the number of total arrangements/permutations of the two dice rolls. They did not use the total # of sums possible, which would be 11. We are not interested in the possible sums of two rolls, as such you are correct – they would give us 1-6,2-6,… 6-6 and some 11 ( I don’t know I didn’t count). We are interested in the number of rolls of two dice to result in one event – the sum of 6. In the list-product problem, the book counts 8 total possible outcomes from the 8 possible products between the numbers within the two lists (2,5,15,1,10,25,30). They did not use the total # of numerical arrangements, which would be 17 (3*3*2, minus one because picking 5, then another 5 is the same thing as its reverse) My question is, is this an error in the book or are the different approaches because of the different nature of the two problems (dice roll vs pick-a-number)? And if these were official ETS questions, how would I be expected to answer? In your book, the author has mistakenly discounted the products of 1*5 and 5*1 and counted this as one outcome, hence 8 possible outcomes, i.e. 9-1=8. But this is wrong as even with the same products the two numbers below to different sets hence both have their assigned probabilities to be picked up from the lists A and B. Let’s solve this questions differently, Suppose we must have odd product which is possible under one single condition à odd*odd=odd. The probability that list A has an odd number is 1 or 100% and the probability that list B has an odd number is 1/3. hence 1*1/3=1/3. Now the vice versa, the probability that list B has an odd number is 1/3 and the probability that list A has an odd number is 1, hence (1/3)*1=1/3. We cannot add up these two probabilities (1/3 and 1/3) because the two lists A and B represent distinct pools and our selection for the product of numbers doesn’t DEPEND on our selection from either the set A first and set B next or the set B first and the set A next. To prove this we need to look into number theory and the distribution rule for multiplication à a*b=b*a. So we don’t over-count and leave only 1/3.
  9. no single twin is alike for parents. ETS has mommed and papped its question pool so that even if they look alike, such as twins, they are always different. The trick in your last test was tied to your false association of previously seen questions from an old administration with the questions of your recent test.
  10. perhaps your brother's diagnosis with ADHD affected your thinking of the same symptoms characteristic for this disorder. However, you cannot set diagnosis on yourself, even if you were a doc, still the diagnostic process is to complicated to be fulfilled by an affected individual oneself. The thing that you keep five things at once in your mind, alone, should suffice for the indication of your brain functioning properly.
  11. that you score 3.5 or 4.0 doesn't make a big difference for AdComs who are aware of ETS scoring interval if you scored 3.0 then alternatively they would be looking at people's 2.5 within the same interval. Hence no need to retake 3.5 AWA score unless you score 5.0 or better next time.
  12. 34/50 will land you around 159 for the verbal. btw, i too sat for pbt last saturday and missed one question at the end of second math section. I also think that one question in the first math section was marked wrong, I was confused with that problem's wording. Nevertheless, I expect q170, as even with 3 mistakes in math section on pbt hard variation one should get 99 percentile in quant. I think I had hard variation of the test, as I am usually pretty fast in solving GRE math questions. In the verbal I will be hardly able to get over 60 percentile sorry non-native speaker and the test was hard at this time
  13. swisschocolate your consistent posts on gre topics make me to think that you made up your mind about repeat test. Is that true? do you plan to take gre again?
  14. what's ur background and how you came to score 98 percentile in math?
  15. percentiles of the old format gre cannot be shifted anymore new, revised gre percentiles were reviewed in July and some deflation took place with the quan percentiles
  16. because in a class you are delivered pattern methodology on how to approach the test. Usually these things cannot be generalized and improve the score as various people reactions differ under the same testing conditions. If you were to hire tutor I could understand that you get special treatment and your test results are analyzed by an experienced person. In a class however this is not possible, as well as it's not achievable by subscribing to online courses promising 99 percentiles in either section. It's marketing trick to lure people away from attempt to use the test prep resources (time, money) wisely
  17. up to the certain level the prep course are useful. That is if you aim close to 90 percentile you may devote your time and resources to these people running prep companies. If you aim higher, your intended devotion will pay you great loss. You will have to work on your own in order to move forward after landing with scores 160 in math or 161 in verbal.
  18. if you scored below 90 pecentile in any section then I would retake as the chances you score at or above 90 percentile exist with improving AWA. Otherwise I would think and possibly wouldn't retake the test. Since you are aiming tech. area, preferably your math should be >= 90 percentile.
  19. I am not a big fan of determining difficulty level of any section, especially the math on any exam one experimental section may show up and this will have mixed contribution towards the exam takers' intention to find what if the section is harder/easier/not scored. ------------ the biggest lesson I have learned from from taking taking GRE is - 'Be cool and don't think what is easy or hard, do your best throughout the exam!"
  20. hey swiss, in intended to speak for nova's gre math bible and the barron's slipped away in my post
  21. swiss, if you never had to deal with math before GRE or the only math classes you took were high school of college math, then please understand that I, being a math minor, and having spent some time with magoosh, kaplan and manhattan still landed near 160 on math. These books are pure marketing ideas - they don't get you there. Only you working with various questions will be able to improve and score higher on quant. sectino. Again try barron's gre and then see what happens. However, be as much diligent as possible, since only you can get there and not books will take to your desired score.
  22. if you allow me to give you friendly advice, I would offer you to retake the test and apply to all programs you intended initially. Think about this like, it's some nuisance and inconvenience to take the same test multiple times, but considering the marginal cost of retake - that is with each retake and score increase your standing in the list of selected candidates before acads and LORs are reviewed is higher. With every 10-15 percentile increase in scores we get farther in the GRE screening process by AdComs. So prep with the book I mentioned and retake the test. You can practice with hard section problems to save time and retake the test in October.
  23. don't be sad, as I said above I have tried several of prep books and all in vein - they don't show you right strategy for plugging in, substitution and short-cuts. These are however very well addressed in GRE math bible by nova.
  24. Instigate, there is score calculation table at the end of paper-based test edition which is available for free download at www.ets.org/gre please don't restate what I did not say, 130-170 score I only said adjusting incorrect/correct the way you propose is not valid. Where did you get that formula?
  25. this is just meaningless information and any reference to this formula for scoring would be misleading each section on gre is scored differently and adjusted on the percentile ranking table then results of each section are compared and the total score is produced any count of correct vs. incorrect would be misleading as each test is adjusted for its difficulty level
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