The Data Interpretation and Logical Reasoning section of the CAT is probably closest in resemblance to the kind of problems you will be dealing with as a manager. It tests your decision-making ability and speed using limited input. As with all other CAT sections, the most important part of preparation is practice. Needless to say, you should give every practice test as seriously as the real CAT. There is absolutely no sense in giving untimed tests. In fact, giving tests without looking at the watch will only hamper your preparation.
Start off with topical tests in the initial stage of preparation. When you gain confidence in all areas of DI/LR, it is time to start giving a couple of full-length DI/LR tests. After this, merge individual sectional tests and start giving CAT-type full length test papers containing all three sections. Always analyse your performance after every test you give and use tests as a valuable feedback mechanism. If you feel the need, keep going back to topics which you feel require more work and take 1-2 more area-specific tests in that topic. An important thing you need to work on is the judicious selection of questions. Utilize practice tests for this purpose.
The Data Interpretation/Logical Reasoning section can be divided into three key areas:
1. Data Interpretation: This is the calculation intensive portion of the section. It consists of a myriad of graphs, charts and tables from which you will have to glean and analyse data. The key to cracking this area is to quickly identify the key pieces of data that you will require to work on the questions asked. It is not unknown for question-setters of the CAT to try and bewilder students with a large amount of data, most of it unnecessary. As a rule, the more the data presented, the easier the questions that follow, so don’t lose heart if you see a table with 10 columns occupying one whole page. On the other hand, several seemingly innocuous questions may trip you up. Therefore, I would advise you to look at the questions first to get an idea of what data you need to be searching for in the graphs/charts/tables in the main question asked.
Another interesting feature of DI that you as a student can use to your advantage is that, usually, not all questions in a set are of equal difficulty. Specifically, most sets have a ‘counting’ type of question (How many companies have profits more than x%, how many people have incomes less than Rs. Y etc.). Most of these questions can be solved without calculation but by close inspection of the data presented. These I would categorize as ‘gift’ questions designed to test a student’s presence of mind, and should never be missed out on. There are other similarly easy questions in most sets, and you should practice identifying the level of difficulty of questions so you know immediately which ones to attempt and which to avoid. There is no rule that states that you need to attempt all questions in a set, so it is a perfectly valid strategy to attempt selected questions across your DI section, without perhaps completely attempting even a single set.
An unusual source of practice questions that I would recommend for DI is a GRE preparation textbook or software. These contain several graph and chart type questions, most of which are near CAT level. You can utilize these questions in the initial source of preparation to practice reading data off charts and tables, and then gradually move on to tougher questions from CAT preparation material. GRE software comes with the added advantage of an inbuilt timer that keeps you on your toes.
2. Logical Reasoning: This is the tougher (as perceived by most students) portion of the section. It consists of logical puzzles with several questions that follow. The most important and first step to solving an LR problem is to write down all of the information given in a box, table or diagram e.g. if the problem involves seating arrangements at a round table, always draw the table first and then try various permutations and combinations of people seated around it. Once you have drawn the figure for the problem, you are free to think with an uncluttered mind. LR problems usually contain several statements which serve as clues to solving the problem. Thus, the problem should always be attempted in a methodical fashion, and solved step-by-step, because trying to look at all the information at once will confuse even the best of us.
LR problems are usually ‘all-or-nothing’ type, in the sense that if you crack the problem you will have answers to all the questions that follow, and if you don’t you will not be able to answer even a single question. This is because if the logic to the problem is apparent to you, the questions that follow are trivial. Hence, proper selection of problems to tackle is even more crucial here than in DI. Often, students fail to solve a problem after investing 10-15 minutes on it. Since the information they have at the end of that time is not much more than that at the beginning, they cannot answer even a single question in the set and have nothing to show for their effort. Problem-selection is tricky, so if you find that you are unable to make headway after the first 5 minutes, do the smart thing and switch to another set or section. You can always come back later if you have the time.
LR requires the maximum amount of practice among all areas in the DI/LR section. Apart from picking apart problems in your CAT preparation material, try looking for puzzle books or newspaper leisure sections that contain logic puzzles. Puzzle-solving is a knack, and the more you start enjoying logic puzzles, the better you will get at them.
3. Data Sufficiency: This is the third portion of the section, and quite a few DS questions were asked in the last CAT paper. Data Sufficiency problems usually take the form of a logical puzzle, and are in the form of a question followed by two statements. You need to answer whether you can solve the problem using the statements individually, or using both, or whether you cannot solve the problem using the information provided. The key to answering such problems is to pretend like one statement does not exist, try solving the problem, and then pretend like the other statement does not exist and try solving the problem again. These problems are generally tricky, and I would recommend lots of practice and perhaps solving them near the end of your section, after you have solved the other problems.
The DI/LR section is one of the higher scoring sections on the CAT, so you can look to it for help in improving your overall score as well, as long as you devote a good proportion of your time to it. Although recent CATs have had 4-5 question sets, be prepared for 1-2 question sets as well. DS questions have never appeared in sets. Important things to remember while attempting this section are that you need be quick in switching sets if you find a particular set tough, and you need to have presence of mind while solving DI/LR questions. Both of these things can be achieved with the help of practice.