MAKING A MARK - Article by Arun Sharma On Education Times

MAKING A MARK

DATA INTERPRETATION AND LOGICAL REASONING IS A CRITICAL

SECTION OF THE CAT PAPER, YET MOST STUDENTS LOSE MAXIMUM

MARKS HERE. ARUN SHARMA ANALYSES THE REASON AND PROVIDES A

SOLUTION

Although the data interpretation and logical reasoning section has always had one-third

weightage in the CAT paper, it still remains one of the least prepared-for sections. The

major reason for this is that unlike the other sections, it is practically impossible to define

the portion for this section. So, while there is a definite portion that can be outlined for

quants, and at least some contours of a portion definition for English preparation, students

and trainers are at a loss when it comes to defining what to study for DI and LR.

Perhaps, part of the solution to this problem is to come out of your conventional

preparation mode – the way everyone prepares for university examinations ie define

portion, study theory, practise questions, revise theory. Instead, focus on developing an

ability to understand what the basic unit of learning is, when it comes to DI. Looking at it

from another point of view, preparations for the DI & LR section need to be organised under

four basic umbrellas. The first two are:

1) Traditional Data Interpretation-

This is the conventional DI question based on charts and graphs. Skill sets required to do

well in this question type include the following:

a) Your knowledge of some basic areas of quantitative aptitude. Chapters which you need to

be thorough with are ratio & proportions, percentages, progression, and basic concepts of

numbers, averages, and alligations.

b) The ability to understand data and identify variables and their relationships.

c) Calculation skills- you would be well advised to hone your ability to add two digit

numbers, calculate and compare ratios and approximate calculations involving big numbers.

2) Advanced Reasoning Based Data Interpretations:

(First made its appearance in CAT 2003 and can be typically defined as questions that have

some data-based information running behind them, while at the same time one would need

to make certain logical deductions). Unlike traditional data interpretation problems, the data

in these questions is normally presented in a disguised format. So obviously the skill you

need in order to do well in this question type is to develop your ability to interpret data and

discover hidden linkages between the various variables presented.

Let’s take a simple situation to illustrate this:

The anatomy of an advanced reasoning-based DI question:

Suppose there is a narrator who tells you that a bus is going from Delhi to Bombay and it

has two stops in between, say at Ahmedabad and Pune. Next, he tells you the following

statements:

a) When the bus left Delhi, there were 80 passengers.

b) When the bus left Ahmedabad, there were 83 passengers.

c) When the bus arrived at Bombay there were 75 passengers in the bus.

What sense can you make of this information? Suppose someone makes a conclusion that

in Ahmedabad there must have been three new passengers who got into the bus. Would

that thinking be correct?

Obviously, most of you would be confident that we cannot conclude that there were three

new passengers who got into the bus. The difference between the number of passengers

who left Delhi and the number of passengers who left Ahmedabad must obviously be a

function of two distinct variables- i) The number of people who got down from the bus ii)

The number of people who got into the bus

Thus, obviously the only thing you can conclude here is that in Ahmedabad, there were

three extra people who got in (when compared to the number of passengers who got down

from the bus). Why are we using this article to tell you the obvious? Well consider one of the

toughest questions that have happened in the CAT DI sections ever:

The year is 2089. Beijing, London, New York, and Paris are in contention to host the 2096

Olympics. The eventual winner is determined through several rounds of voting by members

of the IOC with each member representing a different city. All the four cities in contention

are also represented in IOC.

In any round of voting, the city receiving the lowest number of votes in that round gets

eliminated. The survivor after the last round of voting gets to host the event.

A member is allowed to cast votes for at most two different cities in all rounds of voting

combined.(Hence, a member becomes ineligible to cast a vote in a given round if both the

cities (s)he voted for in earlier rounds are out of contention in that round of voting.) (Note:

Your interpretation of this sentence should be that, this is one way of becoming ineligible to

vote- if you voted for a particular city in the first round and that city got eliminated, and if

you voted for another city in the second round and that city too got eliminated in that

round, then you cannot vote in the third round. Passenger getting out of the bus anyone?)

A member is also ineligible to cast vote in a round if the city (s)he represents is in

contention in that round of voting. (Note: Do you realise that this is giving us a way of

making a member who is ineligible to vote eligible? Also do you see that after every round

starting after the first round itself, exactly one member will become eligible to vote. 1

passenger at a time!)

As long as the member is eligible, (s)he must vote and vote for only one candidate city in

any round of voting.

Now with this information if you are given the information that 83 people voted in the

second round and there is missing information about the number of people who voted in the

first roundcan’t you realise that 82 people must have voted in the first round? (Obviously,

because from the first round to the second round only one new person would be eligible to

vote. Also, the rule for making people ineligible to vote is only going to come into the picture

in the third round for the first time- so the difference between the number of people who

voted in the first round must

be one less than the number who voted in the second round.)

Further if you are told that, in the third round 75 people voted. Can you see that one

person must have entered and nine people must have dropped out? And those nine people

must have voted for the city eliminated in the first round and then also voted for the city

eliminated for in the second round.

(Isn’t it the same logic as: Bus leaves from Delhi with an unknown number of passengers,

reaches Ahmedabad and when it leaves Ahmedabad there are 83 passengers. It is also

known that no one is allowed to get down in Ahmedabad and exactly one person entered in

Ahmedabad. Further, one person more enters in Pune and when the bus leaves Pune there

are 75 passengers in the bus. So, obviously nine people must have got down in Pune).

What is surprising is the fact that this question is amongst the toughest to have appeared

in the CAT! And if people cannot correlate the logic of what they see in their daily lives to

what is asked in CAT DI- the CAT can continue to remain a mystery for lakhs of aspirants

every year.

(The author is a CAT trainer and the author of a series of best selling books from

Tata McGraw Hill and can be contacted on educounsellor . as @ gmail . com)