CAT 2010: How to find your comfort level in DI

Data interpretation gives most CAT aspirants the jitters, especially those from non-technical backgrounds. Here Gaurav Bakliwal, of Testfunda.com, share some useful tips on how students can sharpen their DI skills.

The DI section in CAT is basically sub-divided into two types of questions. First, the proper DI questions which have charts/ tables/ graphs and the questions are based on these. Second, Analytical Reasoning (AR) caselets, where data is given in the form of some cluttered information and you are supposed to make a table or match them properly and answer the questions that follow. This article will focus on DI part -- how to tackle it, what are the skills required to crack it and how you can inculcate those skills.

There are two opinions about the DI section -- one set of students feel that it is the easiest section since there is hardly any theory involved whereas another set of students hate it as the amount of calculations involved are huge. Obviously the second set of students is not used to mental calculations or calculating using a pencil and paper. So how do you create a comfort level with figures and calculations good enough to get you through to the IIMs? Here are some tips:

Speedier calculations are must
The basic ingredient of doing well is to master calculations. One should be thorough with multiplication tables up to 20x20, squares up to 30, cubes up to 20 and reciprocal percentage equivalents up to 30 (ie 1/1 is 100per cent, 1/2 is 50 per cent, 1/3 is 33.33 per cent, and so on). The last part is an absolute must.

You would be surprised how much time can be saved by simply memorising these. Division will never bother you again. For instance, if I want to find the percentage increase from 1300 to 1600; basically what I am looking at is 300/1300 x100 which is nothing but 3/13 as a reciprocal. Since I know 1/13 is 7.69 per cent and therefore 3/13 should be 7.69x3, which is approximately 23.1 per cent, I can actually get the answer in seconds without using even pencil!

It also pays to remember various important fractions in percentages. For eg., 37.5 per cent is nothing but 3/8 and 62.5 per cent is 5/8th of a number.

Another approach to calculate fast is breaking the percentage to simpler terms. For eg, if I need to find 64.6 per cent of 273, it would be so much better to find out 66.66 per cent of 273 (basically 2/3) and subtract 2 per cent from it. The final answer will be a little less than this. Therefore it will boil down to 182 -- 2 per cent (approximately 5.4, since 1 per cent is 2.7) and, therefore, the answer is approximately 176.5.

The most important thing is not to know that you need to remember these tables; but it is to actually do them. Here, from experience, I would suggest that one should make a chart of all these tables, squares etc and keep that chart at a place that is visible to you most of the time in a day. You will end up looking at it invariably while doing any non-value added activities and thus automatically it will become a part of you. Never give a stipulated time for mugging these; that time never comes!

Make calculations a part of your life
If you are a serious CAT aspirant; this is something you have to do. Wherever you are and whichever situation you are in, your focus should be on numbers and calculations.

If you are watching a cricket match, calculate the asking run rate based on runs needed in overs left etc; calculate the economy rate of bowlers and try and understand the strike rate of bowlers etc. I am sure many of you will say that you are not interested in cricket, but it's not about cricket, it is about focusing on numbers and calculations.

Or say for instance you are at a petrol pump and want to fill petrol worth Rs 100, try to calculate mentally approximately how many liters of gas you will get, given the rate of petrol is Rs 55 per litre. Don't stop by thinking it should be less than two litres, which is what all CAT aspirants already know. Take the extra effort to calculate how much less than 2 litres you will get.

Here's a quick way to solve this problem: you can get 2 litres for Rs 110. Here you have given Rs 10 less, so the amount of petrol that you get will be less than 2 litres and will be the amount of petrol that you can get for Rs 10. Now in Rs 10, you will get 10/55 litres, since for Rs 55 you get 1 litre. But 10/55 is nothing but 2/11 which is nothing but 18.18 per cent (since 1/11 is 9.09 per cent; reciprocal percentage helps here). So you will get approximately 0.18 liters less or you will get approx 1.82 liters in Rs 100. This might seem difficult to follow for beginners, but these are tips that will help get you into an IIM.

The point is to eliminate the idea that calculations are tedious or tough. The more mental calculations you attempt, the more comfortable you will get at playing around with numbers -- a quality necessary for you to do well in DI.

TestFunda.com is a leader in online MBA test preparation and provides complete MBA prep for CAT and other MBA entrance tests in online, CD and print format. For free content: strategies from CAT 100 percentilers, vocabulary games, puzzles, quizzes, previous CATs, XATs with detailed solutions logon to www.TestFunda.com