In my experience as a part-time instructor for the
GRE at the Princeton Review, I have notced that although Indian students (predominantly those from the engineering stream) are supposed to be higher up the
graph when compared to the global average, the
traps that
ETS sets out for the students are still pretty effective.
I believe that the students make mistakes in the Quantitative section not because they are unfamiliar with the nuances, but rather because they haven't been expressly tested on it with any sort of structuring.
So, with that in mind, I compiled a list of common traps that ETS sets out for the students. Hope it helps :D
# Look for information on sign of quantities -
Very often, the question will refrain completely from mentioning the sign of a quantity. Be very
careful about assuming it's positive. Similarly, for questions involving powers of a quantity, you need to know whether it is
greater than or less than 1.
# Be careful with questions on multiples and factors -
Apply those divisibility tests carefully. And some questions are about common factors or common multiples. It's easy to make mistakes with them. Double check your answers.
# Read graphs more carefully -
Study each graph long enough so you can list all the quantities plotted on it, without looking. That way, as you
answer each question, you can decide, in your head, which part of the graph you're going to read before actually looking at the graph. This is much better than groping around an unfamiliar graph looking for the words or numbers to strike you.
# Check units on graph -
The question may just ask for or repot numbers in different units.
# Check inequality strictness and inclusion of zero -
There is a difference between 'greater than' and 'greater than or equal to'. Be particularly careful when zero is a permitted value.
# Remember spacing and sequences -
An example problem reduces to calculating how many saplings can be planted along a lane N feet long, with the spacing between each sapling being n feet. The answer is < int(N/n) + 1 > and not int(N/n). Remember that the first sapling is planted at one end of the lane.
# Remember to use triangle inequality where possible -
The sum of the lengths of two sides of a triangle is strictly greater than the length of the third side. This can be applied in the less obvious pure geometry problems.
# a/b > 1 is not a good test! -
Tempting as it might be, to check if Column A / Column B > 1, this test breaks down if both are negative.
# Grid-ins -
Since the start of this year, the GRE is supposed to have a new question type called the grid-in. It only has a box where you type in the answer; that's right - no multiple choices!!. They key with this question type is to watch out for the accuracy asked for (nearest 10th, 100th etc)
# Squares and Square roots -
Remember that the square root of a number(usually a square itself) can be either positive or negative. That is, sqrt(64) = either +8 OR -8.
Please feel free to drop a comment if you want any clarifications or feel that I may have left out on any particular traps.
More abstracts about the GRE - Caution with Quants