By MERCIA WIJAYA
March 29, 2016
GMAT Quant High Level Strategic Approach
As a Toga GMAT Quant instructor, I can tell you that you don’t need to know advanced math to do GMAT Quant problems well. In fact, it arguably only requires junior high school math. What makes it difficult is that despite the low level of math, people are rusty with the concepts as they haven’t been exposed to it for years. With 37 questions to solve in just 75 minutes, I’ve seen Indonesian GMAT test takers commonly try to finish each question as fast as possible. Another common thing people do is to finish easy questions quickly to buy more time for more difficult questions. I do not think that these two approaches work for GMAT Quant because, while time is a constraint, accuracy also matters. Thus, it’s important to balance accuracy and speed.
GMAT is also an adaptive test, meaning that only when you get the basic questions right, will you get the more advanced questions. The advanced level questions therefore translate to higher marking points, but this won’t be possible if you couldn’t get the basic questions right in the first place. Unfortunately, I have seen Indonesian GMAT test takers make careless mistakes on basic GMAT Quant questions, which in turn lower their GMAT Quant scores. Hence, although it sounds counterintuitive, it is better for you to spend adequate time on the easier questions to double check the answers before you click the “next question” button to make sure you get the basic questions right.
Practical GMAT Quant Tips:
– Take note on the time spent per GMAT Quant question during your simulation or practice GMAT exams as you will have to pay attention to the time during the actual GMAT test. This can be done with the aid of a mobile phone stopwatch app with a “lap” feature.
– Check the answers and see which category you belong:
- Quick and accurate: keep it up!
- Quick but not accurate: spend more time to check answers
- Accurate but not quick: do more practice. Speed will come with time.
- Neither accurate nor quick: do more practice without taking note of the time spent in the beginning. Aim for accuracy first and then start recording the time again once you feel more comfortable
Lengthy Problem Solving Questions: Structure Your Thinking
GMAT Quant questions with long sentences can appear to be intimidating. Some test takers do not know where to start. Others get distracted with information unrelated to the main question. One way to simplify these questions is by dividing them into several components:
– Variables: make sure to avoid redundancy (cover the question using as few variables as possible). For example, if you encounter a work question with 2 workers, John and Andy, and you assign the variable J to John and A to Andy, then John and Andy working together can be represented as J+A, so no need to introduce it as a new variable Z.
– Equations (or inequalities): an algebraic representation that must be satisfied e.g. 3x + 4y = 20. There can be multiple equations in one question. However, only solve those that will get you to the objective. The rest can just be distractions.
– Objective: what is the question is asking you to solve? Is it the total number or total sales? Make sure to read the objective at least twice to avoid answering the right answer for the wrong question.
Data sufficiency: Solve The Question, NOT The Equation
The objective of data sufficiency questions in the GMAT Quant is to check whether there is enough information to solve a question. However, test takers are NOT expected to solve the question.
There are 2 types of data sufficiency questions; value and yes/no questions. On value questions (e.g. what is x?), we must find whether there’s enough data to find a single value that answers the question. If the data can’t produce any value or produce more than one value, then the information is insufficient. With the yes/no question (e.g. is John older than Mike?), there are three possible answers; always yes, always no, and maybe. Always yes and always no are sufficient to answer the question while maybe is insufficient.
Similar to lengthy problem solving questions mentioned above, data sufficiency questions, especially the algebra heavy ones, could be expressed in variables, equations, and objective. To check if there is sufficient data, we can check the following:
Case 1: same number of variables and (non-redundant) equations: sufficient.
Example: x + y = 5, x – y = 3 has 2 equations for 2 variables (x and y). By adding the two equations, we will get 2x = 8, hence x = 4. This equation is solvable, meaning there is sufficient data.
Case 2: more variables than (non-redundant) equations: insufficient.
Example: we want to find the value of 3 variables: x, y, and z. However, there are only 2 equations: x + y = 3 and y + z = 4. There is no way to solve this. Insufficient.
Case 3: more (non-redundant) equations than variables: “error” (contradiction)
Example, x + y = 5, x – y = 3, x + y = 4 has 3 equations for 2 variables. This is too much information. The first and the last equations turn out contradicting each other (x + y = 5 and x + y = 4 cannot be true at the same time!).
In short, if there are more variables than equations or vice versa, the data is insufficient.
Note: example of a “redundant equation” is x + y = 5 and 2x + 2y = 10 (if you divide both sides of the second equation by 2 it is the same as the first equation)