GMAT Data Sufficiency
I personally love the ‘Data Sufficiency’ section – because it is fun to solve them ! Broadly two reasons (1) It probably may not involve as much rigorous mathematical solving and (2) Each problem is a field of landmines that the examiner has laid for the student. I have a feeling that even for the test setter, the data sufficiency section is the most fun to set and see students fall for simple traps.
If you are a cynic who wonders if any of the questions asked in GMAT / CAT will make you a better manager, the answer is a loud ‘Yes’ for the data sufficiency section (apart from a few others). As a manager, you will take decisions and at each stage you will have to make sure if you have all the sufficient data to take the decision. THIS is the section which puts down the basement for your managerial career.
Some things to remember when solving data sufficiency questions:
1. Never assume anything. Just Never. If they say that x is a number – do not assume that x is a natural number; do not assume that x is a whole number; do not assume that x is an integer or that x is rational. x is a number and that is that. x could be any number.
2. If it is a ‘True’ or ‘False’ question, the answer cannot be ‘May be’. It can be only one of the two. ‘True’ or ‘False’. Simple.
3. Same is the case with ‘Yes’ or ‘No’ questions. Unless you are able to say ‘Yes’ or ‘No’, one can conclude that the statement(s) is (are) insufficient to answer the question.
4. ‘No’ is also a valid answer. The point is whether the statement being examined is sufficient to answer the original question. ‘Sufficiency’ is the core issue.
5. Each of the statement may lead to different conclusions. Consider the simple question:
What is the value of x?
A. x is the an even prime number.
B. x is a prime number greater than 2 and less than 5.
Statement ‘A’ says that x is 2. Statement ‘B’ says that x is 3. You can conclude that ‘Either of the statements are individually enough to answer the question’ – It does not matter that they indicated different values for x.
6. Be super careful about extreme cases. If x has been defined as a whole number – make sure that your conclusion does not change for x = 0. If x has been defined as an integer – make sure that your conclusion does not change even if x is a large positive integer or a large negative integer.
7. Do not spend inordinate time solving equations loosing track of the core issue (which is ‘Sufficiency’). Consider the question ‘Is x a positive number?’
If statement A leads you to conclude that x = root(3 + root (3)). Should you spend time find out the actual value of x? Get back to the core of the question. ‘Sufficiency’ is your keyword. Is x a posive number? It could be positive or negative. You do not care as to what the exact value of x is. All you care is whether x is positive.
You can be fairly certain that there will be data sufficiency questions. The examiner is trying to test the following (amongst others): (1) Is the student exhaustive in his thought process? (2) Does the student jump to conclusions at the drop of a hat? (3) Does the student spend inordinate time in mathematical equations when all I want him / her to test is sufficiency of the statements?
All the best !