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Structure of an argument

An argument has three parts—premises, Assumption and Conclusion.
Premises- These are Evidence, Reasons, Facts or statistics provided by the author to support the conclusion. Premises have to be taken for granted, irrespective of whether they make intuitive sense to you.
Conclusion-This is the author’s point of view or the claim made by the author. This is what needs to be proved or disproved.
Assumption-This is the Unstated part of the argument that is required to link the premises and the conclusion.

Understanding CR questions on the GMAT

Example
Doctor: As established by many research Studies, adolescents who play video games regularly are three times likely to develop carpal tunnel syndrome as are adolescents who do not play video games. Therefore, Federal legislation that strictly prohibits the sale of video games to minors would help curb this painful wrist condition among adolescents. One sentence summary:-Try to summarize the main point of the argument in a single sentence.

Example:
Doctor: As established by many research Studies, adolescents who play video games regularly are three times likely to develop carpal tunnel syndrome as are adolescents who do not play video games. Therefore, Federal legislation that strictly prohibits the sale of video games to minors would help curb this painful wrist condition among adolescents.

Assumption:

The assumption is an unstated premise.
The assumption will always be a new piece of information.
The assumption must be valid for the conclusion to hold.
A right assumption if negated invalidates the conclusion of the argument.

Everyone who reads this article will be more informed about assumption. Rahul received this article in his email. Hence, Rahul is more knowledgeable about assumption.

• The problem most students face is that they have to venture into non-conversant areas.
• No prior knowledge of the topic is required to address RC passages
• DON'T FOCUS ON THE FACTS AND FIGURES
• Most questions will not directly ask you something that is clearly mentioned in the passage.
• So it does not make sense trying to absorb all the details mentioned in the passage.
• Try to see WHY the author has written a paragraph.
• Carefully read the first and last sentence of each paragraph. There is usually no need to focus on the middle part of the paragraph.
• A PHRASE WHICH CAPTURES THE ESSENCE OF THE PASSAGE.
• The topic tells you what subject matter does the entire passage is concerned with.
• GMAT does not ask the topic directly. But it gives you an understanding of the passage.
• While making a passage map – start making notes of each line.
• Focus on WHY and not WHAT
• DON'T WASTE TIME REREADING THE PASSAGE

Fundamental Principle of Counting/Multiplication rule

Q1) How many numbers greater than 999 but not greater than 5000 be formed using the digits 0,1,2,3,4 and 5 if (a) repetition of digits is allowed (b) repetition of digits is not allowed.

Q2) How many 5 digit numbers divisible by 5 can be formed using the digits 0, 1, 2,3,4,5 and 6 if (a) repetition of digits is allowed (b) repetition of digits is not allowed.

Q3) An intelligence agency decides to form 2 digit codes with distinct digits. The code which is handwritten on paper can, however, create confusion when read upside down. For example, the code 91 may also appear 19 when read upside down. How many codes can be formed in which there is no such confusion?

Q4) There is an assignment involving 6 tasks and 6 people. Task 1 cannot be given to person 1 or 2. Task 2 has to be given to either person 3 or 4. In how many ways can the assignment be done if each person is to be assigned only 1 task?

Q) A man forgot the seven-digit phone number of his friend but remembers the following: the first 3 digits from the left are either 242 or 472, the digit 7 comes only once and a number is an even number. If the man was to use trial and error method, what is the minimum number of numbers he has to dial before finally getting the correct number?
Ans. 1215 + 3645 = 4860

Q5) There are n families F1, F2....., Fn in the neighbourhood of X. The number of members in family Fn = n+1. X decides to invite at most one member from each family. If the total number of ways in which he can invite a total of one or more members from his neighbourhood is 2519, find the value of n?

Ans. n=5 since ((n+2)! /2)-1 = 2519

Q6) How many 3 digit numbers are such that if one digit is 6, the immediate next is 7?

Ans. 8 + 7 + 448 = 465

Q) If all integers from 100 and 800 are written, how many times will the digit 2 come?
Ans. 20*6 + 39 = 159

Permutations and Combinations

Q1) There are 15 points in a plane of which 7 are collinear, and 8 are non-collinear. How many different triangles, circles and straight lines can be formed?

Q2) In how many ways is it possible to arrange all the letters of the word EQUATION such that (a) no two consonants are together (b) all the consonants are always together?

Q3) In how many ways is it possible to organize a mixed doubles tennis tournament involving six couples such that no husband and wife play in the same game?

Ans. 6C2 X 4C2 X 2 = 180

Q4) In how many ways can a person invite 8 friends to a party if he has to invite (a) at least 1 of them (b) at least 2 of them?

Q5) Let S be the set of first 10 whole numbers. How many subsets of S can be formed such that each one of them contains 7, but none of them contains 8?

Q6) Let X =(1,2,3,4,5,6,7) and A=(3,4,5). If A Ê? B = (3, 4), how many subsets of X can B represent?

Ans. 24 =16, since B cannot have 5 in it.

Chess Board

Q1) How many squares and rectangles are there in an n x n and an m x n grid?

Q2) In how many ways is it possible to select two white squares from a chess board such that (a) they are always together in the same row or column (b) they are never together in the same row or column?

Q3) In how many ways is it possible to select one black and one white square from a chess board such that (a) they are always together in the same row or column (b) they are never together in the same row or column.

Q4) In how many ways is it possible to select two unit squares from a chess board such that (a) they share a common edge (b) they share a common corner.

Q5) In how many ways is it possible to select two unit squares from a chess board such that lie on the same diagonal?

Q6) In how many ways is it possible to place two rooks on a chessboard such that they do not attack each other?

Q7) In how many ways is it possible to two select three unit squares from a chess board such that only one of them shares an edge with the other two?

Q8) There is a 5 x 5 square grid, with each cell having a distinct identity. In how many ways can 3 identical coins be placed in the grid (with at most 1 coin in each cell) such that no 2 coins are in the same row or column?

Answer. (25 x 16 x 9)/3! = 600

Permutations of alike things

Q1) Let 105 < K < 106, where K is an integer. Then how many different K exist such that the sum of the digits of K is (a) 3 (b) 4.

Q2) In how many ways can a person reach from A to B if only forward or upward movement is allowed?

1. 
   Q) Consider a rectangular grid of lines formed by “m” parallel lines intersecting “n” parallel lines running perpendicular to them. How many different paths along the grid are possible from top right corner to the bottom left corner if
   a) only upward and forward motion is allowed?b) only diagonal, upward and forward motion is allowed?
   Ans.
    [(m + n-2)!]/ (m-1)! X (n-1)!

   Q) In how many ways can you go from A to B such that a certain portion of the grid should not be visited?
   Q3) In how many different ways can four letters of the word EFFERVESCENCE be (a) selected (b) arranged?

   Q4) In how many ways is it possible to place three identical coins in a 5 x 5 grid (with at most one coin in each cell), such that no two coins are in the same row or column?

   Ans. 300 = (25x16x9)/3!

   Rank of a word

   Q1) Find the rank of the words (a) HEAT (b) WHEAT (C) FLOWER (d) MAYANK.

   Ans. (d) = 200

   Circular permutations

   Q1) In how many different ways can 5 men and 3 women be seated around a circular table such that no two women sit together?

   Q2) Ten friends go out to a restaurant for dinner. There they see two circular tables -one with 6 chairs and the other with 4 chairs. In how many ways can they sit around the two tables?

   Partition concept

   Q1) How many positive and non negative integer solutions exist for: 10 < (a + b + c + d) < 20

   Q2) Find the number of terms in the binomial expansion of (a + b + c + d)20.

   Q3) In how many ways can 25 marbles be distributed among P, Q, R and S such that P gets at least one marble, Q gets at least 2 marbles, R gets at least 3 marbles, and S gets at least four marbles?

   Q4) How many numbers less than 105 are such that the sum of their digits is 10?

   Q5) In how many ways can a thief steel 10 houses in a line such that no two of them are together/adjacent?

   Q6) Ten soldiers are standing in a single row. Their commanding officer wants to select any three of them such that there are at least two soldiers between any two of the soldiers selected. In how many ways can this be done?

   Ans. 6C3 = 20 since a + b + c + d = 7 where a, b, c, d are the gaps between the three soldiers selected

   Q7) Four unbiased dice are rolled. In how many ways can a sum of 19 be obtained?

   Ans. 56 ways. It is same as solving a + b + c + d = 5

   Miscellaneous

   Q1) Five horses are competing in a race. How many different finishes are possible if ties are also allowed?

   Q2) Derangements à d (n) = (n-1) [d (n-1) +d (n-2)], n≥3

   d (1) = 0, d (2) = 1, d (3) = 2, d (4) = 9, d (5) = 44

   Distribution

   Q) There are 4 letters and 3 letterboxes in which these letters are to be posted. Find the number of ways of doing this assuming:
   1) All letter are distinct, and all boxes are also distinct

   Ans. (Groups)Objects = (3)4

   2) All letters are distinct and boxed are identical

   Ans. 14 – (4,0,0), (3,1,0), (2,2,0), (1,1,2)

   3) All letters are identical and boxes distinct

   Ans. 15 – partition concept

   4) All letters are identical, and boxes are also identical

   Ans. 4- (4,0,0), (3,1,0), (2,2,0), (1,1,2)

GMAT is not really tough at all but its a bit chellenging. it is  required meticulousness, dedication and planning. There are following tips and strtgeies that will help you in getting good score - 

Make yourslef familiar with computer: As this is lengthy computer based test, so one should get familair with computer typing. 

Do online pratice from: Do some online pratice such as various realted quiz and othr things. 

Use process of elimination: One should be aware of how you can eliminate an obtion which is not within the scope, too extreame. It is far easier to eliminate wrong answers than it is to pick the right one. So, when you are not sure about  answer choices on a given question, try to eliminate all the wrong ones first. Make a case for why each one is wrong. The choice that is the best to disprove will likely be the right answer.

For Sentence correction: Go through the fundemantals of Grammar which will help you eliminating the answers. Go through concise and short answers if you dont have any other valid reason to eliminate. 

For reading comprehensions, read the passage first: When you come across a passage based questions, read the passage first, not the question. This is generally believed that  the better strategy for two reasons. First, you can only see one question at a time, but there will be three or four questions for each passage. Second, even questions that seem to be about a small detail or sub-topic will require a holistic understanding of the passage to answer correctly. You actually have a better chance of identifying the right answer in the majority of questions if you aren’t biased toward one detail or sub-topic, but are reading for the main idea instead.

For crtical reasoing: Read the quetsiobn stem first then the stimulous as question stem will guide you where does this question belong to each categories of question completely different approach. 

For gmat Quantitative aptitude questions get your fundamentals cleared which will help you in getting good score.

Best of luck!