gmat data sufficiency

Preparing for GMAT: Important Links for You

Dilip Oak's Academy

Gathered together here are some useful links that will help you get prepared for that all-important exam!

Reading Comprehension

Data Sufficiency

Read these blogs and never get confused about Data Sufficiency questions on the GMAT again:

Integrated Reassoning

Wondering what Integrated Reasoning is and why it was introduced? Find out with these simple explanations.

Analytical Writing Helps

Problems with writing good essays in English affect almost everyone. Here are some important links on cutting out the mistakes that pull you down.

Find out about:
– how to how to move smoothly from one paragraph to another by using transition words and phrases effectively
– tips on how to improve sentence clarity through using parallel constructions, transition phrases, clear pronoun references and other grammatical devices
– when to use capital letters and when to go with small case:
– making sure you don’t confuse your a’s, an’s and the’s:
– advice on proper subject-verb agreement

Tackle Options in GMAT DS Questions the Oak’s Academy Way

Dilip Oak's Academy

~ by our Quantitative Reasoning Faculty

 

Step 2 of the Approach to DS Questions: Tackle the Options the Oak’s Way

Step 1 of the approach dealt with carefully reading the question statement (see previous blog). Once that is done you have to deal with the options, which are standard in DS questions:

(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

(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 are needed.

To deal with them in the most systematic way possible just follow the sufficiency/insufficiency table below. It offers the best way of thinking through the options

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Solutions to GMAT DS Questions

Dilip Oak's Academy

Solution to Question in ‘Tackle Options in GMAT DS Questions the Oak’s Academy Way’ Blog Post

Question:

Given that a, b, c, d, e are positive integers and that ‘b’ is an odd integer, is the product (a+b)(a+c)(a+d)(a+e) an odd integer?

(1) a is an odd integer

(2) c is an even integer

 

 

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A Few Great Tips on How to Tackle the GMAT DS Questions

Dilip Oak's Academy

 by our Quantitative Reasoning Faculty

In last time’s blog we looked at why DS is so important in GMAT. In this one we’ll take a look at the 3 key things that you need to do in order to tackle this unfamiliar question type. There are:

 

1. Learn the Options

The first step in learning DS is to get absolutely familiar with the options. Fortunately, in DS, this is easy because the five options are always as follows:

(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

(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 are needed.

 

2. Remember the Aim

Remember, in DS our aim is NOT TO FIND THE FINAL ANSWER to the question but  just to verify whether the INFORMATION GIVEN IN THE TWO STATEMENTS IS SUFFICIENT TO REACH TO THE FINAL ANSWER!

So while solving the question if, at any intermediate step, you realize that you can reach the final answer then QUIT and mark the option accordingly.

 

3. Understand the Approach

Now let’s have a look at how you should approach DS questions.

Step 1: Carefully Read the Question Statement and Find the Crux of the Question

After closely examining the question statement and before you read the information given in statements (1) and (2), ‘identify the crux of the question’. What I mean by ‘the crux of the question’ is the piece of information that is the key to the solution. Sometimes you have to think a little bit before you get it. But once you have it, it will lead you straight to the answer. For example, have a look at this question statement:

 

If x and y are distinct positive integers then:

 

 

 

 

 

(1) x = 2 (y + 3)

(2) x2 = y2 + 4

 

Now, if you have lost touch with maths, just the sight of that forest of terms is enough to want to make you give up. But again, remember that we are not at all interested in solving this inequality. We just need find out whether the expression on the left hand side is positive or not (that’s what is implied by >0) – and this is a much simpler matter! Further, in this mass of algebraic symbols is a key that reveals itself when you examine about the expression and think about it a little.

In order to get this key, the first thing to do is to carefully observe the question statement. First and foremost, it says, that x and y are distinct positive integers. This is a very important piece of information – and you’ll understand why in a moment. Secondly, if you observe the numerator of the expression on the left, it consists of additions throughout. Given both these pieces of information, the numerator has to be positive in nature: it is the sum of distinct positive integers (which is why the information about x and y was important). By the same logic, even the second bracket in the denominator has to be positive. The only unknown factor, therefore, is the first bracket in the denominator, i.e., (x – y) and this is what holds the key to the entire problem.

The entire expression will be positive if and only if (x – y) > 0, in short, if x > y. On the other hand, if x < y, the whole expression will be negative. So, the whole gigantic problem is reduced to an extremely simple question: is x > y? Once we have arrived at this conclusion, cracking the rest of the problem is really easy: any information about the relative magnitudes of x and y will be sufficient to arrive at the answer! Thus, in this case, the crux of the question (the key to the solution) is realizing that all we need to find out in order to answer this question is whether statements (1) and (2) allow us to decide whether x is bigger than y or vice versa.

Once you have reached this stage you are can confidently take on the options of this seemingly insoluble problem. The discussion above takes care of Step 1 of the approach i.e. carefully reading the question statement and finding the crux of the question. In the next post we’ll look at Step 2 of the approach: tackling the options in DS questions – and we’ll be giving you tips that will reduce the complexities to a few simple steps! Watch for the tips in our third DS blog post next week.

The Importance of Data Sufficiency Questions in GMAT

Dilip Oak's Academy

~ by our Maths Faculty

 

My opening GMAT blog post will focus on Data Sufficiency, an important and unique Quantitative Reasoning question type in GMAT. Later on we’ll take up some sample questions to illustrate how to tackle this strange and interesting question type but first we will look at a fundamental point: why is DS important? Well, look at Figure 1 below

Figure 1

What this pie chart tells us is that, out of 37 questions in the GMAT Quantitative Reasoning section, you can expect around 22 to 23 will be of the Problem Solving (PS) type and 14 to 15 of the Data Sufficiency (DS) type.

Now, maybe you’re thinking that what this highlights is the importance of Problem Solving questions. But that is only the most obvious thing that the data says. The other important thing that it tells you is that if you want a good score in GMAT, you cannot afford to neglect Data Sufficiency. On the contrary, DS questions play a crucial role in converting mediocre GMAT scores into first-rate ones, so, if you ignore DS questions, that great GMAT score you are looking for may never be yours. Here’s why.

When you are through with your initial preparation and have given 3-4 mock GMAT tests, like most other students, you will probably find your scores stagnating. There are various reasons for this, but, in Quant, if you find that your raw score is fluctuating between 43 and 46 out of 60, the reason will usually be low accuracy in DS.

The most important reason why many students don’t achieve high accuracy in DS is that they don’t think the way that DS demands. We never solve such questions either in school or in college so, we don’t really understand them and so, we end up ignoring or trying to avoid DS questions. But that, is a big mistake! Remember the stats: you can’t think of getting a good score in GMAT without mastering DS questions. So, how do you deal with the difficulties that this question type throws up? Watch for our next post and find out.