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Data Sufficiency


Ever heard of a Math problem that you actually don't have to solve. If you have just started your GMAT prep, then this can be confusing. Don't worry! With some practice, your mind will be trained to think like a DS Wizard. Follow these 10 tips and you will be on your way to mastering GMAT Data Sufficiency.

1. Familiarize with the Answer Choices

No excuses: On Data Sufficiency, they’re always the same! Know in the blink of an eye what choice C is. On test day, if you find that Statement 1 is insufficient, be able to cross out choices A and D without hesitation.

2. Takes notes efficiently

Each statement alone will be sufficient if both of the statements on their own contain all the information necessary to answer the question. The statements will be sufficient together if they contain every piece of necessary information between them. Take the area of a parallelogram: Do you need to know every side length to determine the area? If you have every side length, can you find the area?

3. Don’t look at the statements together.

Statement 2 may tell you that x is negative, but that fact has no bearing on Statement 1 when viewed by itself. Explore all the possibilities offered by each statement individually. If you’ve...

Categories : Data Sufficiency

Data Sufficiency questions are not the same as your regular "Find the value of x" question. GMAT DS Questions require you to adjust in your approach to Math Problems. You are not primarily concerned with the final answer, but rather whether you have enough information to get you to that answer. For example, if you’re asked to find the value of x, and a statement tells you that 300x + 257 = 1345, you know that this statement is sufficient, because you can perform arithmetic on that equation to isolate x. Are you going to perform it? No, because it’s too complicated and you don’t need to! All you’re concerned with is whether you can find the answer.

It might strike you as odd, but because of this principle, you can tackle some supposedly difficult DS questions without writing down a single equation or calculation! Sounds too good to be true, but in actuality, it makes a lot of sense. Remember, in business school you’ll be given data in case studies, and you’ll be expected to determine relatively quickly what information is relevant. DS questions are perfect for testing this ability because you have to look at the information given to you and cut to the heart of what is most important about that information.

As an example, let’s look at this rather wordy DS problem:

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During GMAT Preparation, Critical Reasoning and Data Sufficiency sections require a great deal of adjustment compared to GMAT Reading Comprehension and Sentence correction, as the latter follows a format that you have seen in Computer Adaptive Tests, undergraduate level tests, and other job interview evaluation. The linear thinking that involve variables, data substitution, rules, and logical thinking might not completely work for 700+ GMAT CR and DS sections.

Let us look at a simple example that will show how our logical minds work, and the assumptions that come into play while solving a problem. An L-Shaped object has 4cm and 2 cm sides.


GMAT Assumption Mistakes - Figure 1
How do you divide this L-Shaped object equally? Immediately our mind will parse towards vertices that can divide this object. And as you might have guessed it, a line from Point A to the opposite vertex divides the L-Shaped object equally.

Dividing the Object into Two Equal Parts

...


GMAT Data Suffficiency RephrasingTo score 700+ on the GMAT, test takers must develop a strategy to answer the Quant questions in 2 minutes and Verbal questions in 1 minute & 20 seconds. Data sufficiency questions can be solved well within the 2-minute mark, most likely in 1 minute and 30 seconds if the conditions and question are rephrased. Not all questions will be required to be rephrased but there are certain conditions where this technique is extremely useful, especially when concepts in Ratio & Proportion, Equations, Inequalities & Divisibility are tested.

Equations

This is the most common question type where rephrasing the conditions might be useful, especially in quadratic equations, and questions that require finding roots.

Let us look into a quadratic equation question type

For the following equations with positive roots, the value of k is greater than one

1) 3x^2 +5x + 2k = 0
2) (x+1)(3x+2) + 2k - 2 = 0

1) Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient to answer the question asked.

2) Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient to answer the question asked.

3) BOTH...

Categories : Data Sufficiency

GMAT Data Sufficiency Movie TheaterWhat was the revenue that the movie theater earned from Friday to Sunday if the occupancy rate of its three screens 1, 2, and 3 were the following?

                       Friday       Saturday     Sunday         
Screen 1           85%            90%            90%
Screen 2            65%           50%            65%
Screen 3            50%           20%            15%   

1)    There are two ticket types in each screen  – Silver and Gold, Silver sold at $35 - $10 less than Gold
2...


Q) Is the sum of all the numbers between prime numbers x and y an even or an odd number?

1)    x = 3  y = 31
2)    y is the largest two digit number, x is even

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.

Answer

To answer data sufficiency questions you don’t have to solve the problem. You just have to find the sufficient condition to prove the answer choice.

Question:  sum(x+1, x+2….y-1) = Odd or Even

Condition 1: x = 3  y = 31


Sum (4, 5,….30) = odd or Even

You don’t have to solve this but since you are aware of the sequence of numbers between x and y, the answer can be found.

Condition 1 is enough to answer the question

Condition 2: y is the largest two-digit number, x is even

The question mentions that x and y are prime numbers. Condition 2 provides two more additional information about the prime numbers.

Y is the largest two-digit number

Largest...


GMAT Data Sufficiency Process of EliminationOnce GMAT test takers have learned about the fundamental concepts tested in the exam, focus should be on saving time for each question. In GMAT, each question should be answered in just under two minutes. Data sufficiency follows a format where a question is followed by two statements, labeled as (1) and (2), and five answer choices in the format:

a) Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient to answer the question asked.

b) Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient to answer the question asked.

c) BOTH statements (1) and (2) TOGETHER are sufficient to answer the question asked, but NEITHER statement ALONE is sufficient to answer the question asked.

d) EACH statement ALONE is sufficient to answer the question asked.

e) Statements (1) and (2) TOGETHER are NOT sufficient to answer the question asked, and additional data specific to the problem are needed.

Process of Elimination techniques will allow you to complete the GMAT DS questions in less than one and half minutes.

Let us consider a few scenarios:

Statement 1 is insufficient:
...




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