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Preparing for General Mental ability and Basic Numeracy for CSAT

Quantitative section takes about 10-12 % of the CSAT paper. The number of questions varied from 3 to 7 to 11 till last year.


Quantitative section takes about 10-12 % of the CSAT paper. The number of questions varied from 3 to 7 to 11 till last year. The questions were relatively of lesser difficulty level, hence it is easy to crack this part of the paper. However a few core skills need to be developed. These include a combination of accuracy and speed, the ability to perform simple calculations under pressure and the ability to use reasoning while solving mathematics questions.

Considering the nature and scope of these skills, practice should become imperative for any student. The basic understanding and grasp of concepts is vital and should never be looked over. Along with these, one need to develop a certain set of advanced skills and learn a few short cuts so as to minimize the time you spend on each question.

Given below are some of the tips to master this section along with some examples below to reinforce those tips.

► Learn to master the basics: Majority of questions are asked from the Arithmetic section with the odd questions asked from the Modern Maths section ( viz. Permutation/Combination, Probability and Set Theory). Hence focus should be to master the basics of these sections. Develop strong fundamentals for each of the above mentioned categories. Remember weakness in one area can have a negative effect on multiple sections because most of the time the question requires understanding of concepts of two different areas. In addition to this, one should always know the amount of weightage one should give to each sub areas of quantitative ability while preparing. For example, recent trends show that numbers, time speed distance, permutations and combinations are some topics that are frequently tested in the examination. Questions from topics like Mensuration, time and work and probability vary from year to year. However questions from topics like sets, clocks, pipes and cisterns, are hardly been seen in recent years. This is not to discount the importance of these topics but one should always pay emphasis to topics which are in vogue.

► Focus on application: The formulae plays an important part in attacking a question, but more often than not,the questions that are asked is a combination of formulae, hence the focus should be on application of formulae. Also exceptions to the formulae should also be kept in mind while solving the questions. An example below shows this

1. The LCM of 2 numbers is 272, while their HCF is 8.If one of the numbers is 16, what is the other number?

The formulae is Product of 2 numbers = their LCM × HCF. Applying this we get the other number to be 136.So a straight-forward question.

2. The LCM of 2 numbers is 200, while their HCF is 2.If one of the numbers is 16, what is the other number?

Applying the same formulae, we get the other number to be 16.But the HCF of 25 and 16 is 1, but the question says the HCF to be 2. Hence this question is a wrong question. No such set of numbers exist.

3. The LCM of 2 numbers is 14, while their HCF is 5.If one of the numbers is 35, what is the other number?

This question is again a wrong question, since HCF is always a factor of LCM and here 5 is not a factor of 14.

► Judgmental ability: Always judge the question before attempting the section and try to find out the easy ones on the basis of your skills, ability and strengths. Some problems which may be easy for others may be hard for you and vice versa. Also have a basic idea as to what the question is actually trying to ask. The question might contain information and combination of options, which will make it a little confusing to mark the correct option. An example below shows this

The rate of inflation per year  is 1000%. What will be the cost of an article 2yrs from now, which costs 10 units now? A) 1000  b) 1100 c)1210 d) 100

The inflation is 1000%, which means the price rises by 10 times and hence becomes 11times. Hence the price will be 10×11×11=1210. To confuse you, the question gives options which are 10 times and 100 times of 10.

► Practice and Practice: The way you practice will gives you an edge over others. Given below are some practice tips while going through a quantitative aptitude text book.

1.While  going through a particular topic in a text book, Clear the basics part first by going through the fundamentals of that topic..Fundamentals include the formulae and application of that as well.

2. Practice the examples first. Go through the first 2-3 examples by going through the solutions understanding each step thoroughly. Read carefully and try to understand what it is really being asked in each question.

3. Try doing the next 2-3 examples yourself. If you are not successful, look at the solution .Try to analyse as to why you are making the mistake. Either you are making a calculation error or there is a problem with the funda itself. If you are making a silly calculation mistake, promise yourself to be extra careful. If there is problem in understanding of the fundamentals itself, then go through topic once again to clear the chinks .

4.  Try doing 2-3 very difficult problems on that topic. Give youself a particular time in which to solve them. Scale it up to 10-12 difficulty level problems and then see your accuracy as well as speed on that topic. Practice  as much as possible on that topic.

5. After you have done sufficient number of topics in a particular subarea (Arithmetic, P&C, 3D Mensuration etc), try doing a test on that. To avoid being taken by surprise, it is important to do a number of tests on different patterns, within the given time frame. Analysis of each test is a must so to know the scope of improvement in that particular area. The analysis must have these parameters

a. Which questions to select?

b. How much time to invest in a particular question?

c. Where am I making a mistake? Follow step 3 as given above, accordingly.

At each step, needless to say time plays a big role in the preparation, so be focused on time. Maintain a time discipline, but don’t be rigid right at the beginning of your preparation.

► Test taking strategies:  As you know that in spite of a good theory background and n-number of mock tests, the examinee still fails to devise a proper strategy of attempting a test, mainly because of the fear of the unknown. It is like a cricket captain deciding to field in a final match after winning the toss because past records suggest that(may be a dew factor), but absence of a strategy if the ground conditions change on that day, will ensure that his previous efforts comes to nothing.

As already stated previously, CSAT tests 3 skills

1. Time management   2. Decision making   3. Pressure handling capability.

Having known that you are going devote 25 mins to this section of 8 questions (let’s assume), devise a process in which to make the best use of that 25 mins. By the time you get to sit in CSAT, you will have this knowledge about the general feel of the section (Mocks play a big role in this endeavor). If most of the questions you scan are confusing to solve, try to identify the easy questions (sitters), which you can attempt straightway. If you go through any paper of past years, you will find that at least 1/3rd of questions can be attempted if one has a reasonable knowledge of the fundas. There might be some questions which seem pretty straight forward when you started but soon you understand that there are twists to it. The percentages of those questions are very less. Leave the questions which are taking more than 2-3 mins to solve.

While solving the question, put down all the given information in a neat and structured manner as possible, after which you will be in a position to decide whether you can proceed further or whether you should leave that question and move on. Also, try to check for alternative approaches like elimination/substitution of choices, which often save a lot of time and pay rich dividends. These can be mastered thorough practice.

Given below are 3 problems which will give us an insight about how to choose a question.

1. The probability of Suresh solving a problem is 2/5  , Ramesh solving it is  1/3 and Aakash solving it is  . If all three try to solve the problem, calculate the probability of problem being solved.

A] 31/35  B] 29/35  C] 8/105 D] 1

2. There are eight dice each having 6 faces, which are numbered with the first six odd natural numbers. These dice are thrown simultaneously; find the number of ways in which the sum of the numbers on the faces of the dice equals 43.

A] 10C6 B] 5040 C] 106 D] None of these

3. In how many ways can 30 identical balls be divided into 3 groups?

A] 146 B] 75 C] 76 D] 91

1. This problem says that the problem has to be solved by at least 1 person. So we will not multiply the probabilities. There is one option, which has exactly this option pertaining to


2.This question looks like there can be number of cases but you have to know that the sum of 6 odd numbers cannot be odd. So there is no such case which has the sum to be 43. So this is basically a number system question being rephrased into a P&C Question. The correct option is D.HENCE THIS IS AN EASY QUESTION.

3. This problem at the outset looks to be an easy question, but go within there can be a number of cases which are enumerated below.

The number of balls in all the groups can be same in only one case: (10, 10, 10). The number of balls in exactly two groups can be same in these cases: (1, 1, 28), (2, 2, 26), …, (14, 14, 2). These are 14 cases. The number of balls in the three groups can be different in these cases:

First group has 1 ball: (1, 2, 27), (1, 3, 26), …,.(1, 14, 15) (These are 13 cases)

First group has 2 balls: (2, 3, 25), (2, 4, 24), …, (2, 13, 15) (These are 11 cases) (we cannot take (2, 14, 14) which has been counted earlier)

First group has 3 balls: (3, 4, 23), (3, 5, 22), …, (3, 13, 14) (These are 10 cases)

First group has 4 balls: (4, 5, 21), (4, 6, 20), …, (4, 12, 14) (These are 8 cases)

And so on.

So, total number of cases = 1 + 14 + (13 + 11 + 10 + 8 + 7 + 5 + 4 + 2 + 1) = 76.


Hope I cleared some of the doubts regarding the GMA section for CSAT.

Practice books which will help you in getting a grasp of topics are:

1. Quicker Maths By M. Tyra

2. Quantitative Aptitude by Abhijit Guha


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