why one finds it difficult to follow once on reasoning
Answers
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 analyze data. However, the question which often strikes Aspirants is Why you are tested in Data Interpretation? 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.