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  • CAT - 2009 - Quant Discussions

    Updated: Oct 25, 2024
    Views: 1.4K
    Hello Ceans,

    In this thread we will discuss all the methods , short cuts , easier methods to crack the QUANT part of CAT exam .

    Mathematics is a bit easier section , we will discuss each topic for 3 days say Algebra , numbers etc etc

    I will start the discussion put here the basics and people please practice the respective section and post your questions here such that we can discuss it.

    please post a tuff question here , because the question which is tuff for you may have a simpler solution with other CEan.

    So as a group we will make the Quant section crackable .

    You can also post questions if thats too big to type 😉

    Book : Arun Sharma , Chapter -2 , LOD -II - Q- 3 (Example)

    people with that book will answer that question.

    please post your suggestions.
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  • ms_cs

    MemberMar 9, 2009

    Nice, ...I am having R.S.Aggarwal Book...I can post the questions from that book...
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  • Saandeep Sreerambatla

    MemberMar 12, 2009

    hello ms_cs
    if you are preparing for cat exam RS aggarwal is no longer useful.
    please get a book by arun sharma or another stuff, basically RS aggarwal is a easy version not much useful for CAT takers.
    😎

    feel free to post your questions.
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  • ms_cs

    MemberMar 12, 2009

    Whether Agarwal book is helpful for quantitative aptitude test conducted during interview..?.I thought that it will useful for both.
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  • Saandeep Sreerambatla

    MemberMar 12, 2009

    Hello People,

    Here i have an idea , instead of you people posting questions i will post the difficult questions.
    initially i will start posting stuff about the chapter say numbers some topics and you people can read them and if i find any interesting questions i will post it here.

    We will discuss the chapter for some N no of days depending upon its weight age in CAT exam.

    Wat say guys?

    😎😎
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  • whizkid123

    MemberMar 13, 2009

    Trishna's Quantitative ability is a very good book.has many difficult questions.Is there weightage for specific chapters in cat quant?


    #-Link-Snipped-#
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  • ananth22290

    MemberMar 13, 2009

    Hey,
    I am ready. Start asking questions.
    Lets crack CAT 2009😁
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  • Saandeep Sreerambatla

    MemberMar 24, 2009

    This thread went dead.

    Ok lets see...
    Tell me what are the kinds of numbers?
    i mean the classification of Numbers?
    😎
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  • Anil Jain

    MemberMar 24, 2009

    Numbers are mainly classified as Complex, Real, Rational, Integer, and Natural Numbers.

    CAT is not a subjective paper I guess.. 😁

    -Crazy
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  • Raviteja.g

    MemberMar 24, 2009

    ok.
    let me put a question here.
    Q: Log[(tan 2)(tan 4)(tan 6)....(tan 86)(tan 88)] = ?

    a) 0
    b) 2
    c) 1
    d) infinity
    I think it is easy .
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  • Anil Jain

    MemberMar 24, 2009

    Raviteja.g
    ok.
    let me put a question here.
    Q: Log[(tan 2)(tan 4)(tan 6)....(tan 86)(tan 88)] = ?

    a) 0
    b) 2
    c) 1
    d) infinity
    I think it is easy .
    tan a = (sin a/cos a)
    Sin 2 = Cos 88
    similarly cos 2 = sin 88
    So [(tan 2)(tan 4)(tan 6)....(tan 86)(tan 88)] = 1
    and Log 1 = 0, so answer is a)

    Correct me if I am wrong?

    -Crazy
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  • Saandeep Sreerambatla

    MemberMar 24, 2009

    crazyboy
    Numbers are mainly classified as Complex, Real, Rational, Integer, and Natural Numbers.

    CAT is not a subjective paper I guess.. 😁

    -Crazy
    Thats Correct.
    Its not subjective , but if we can classify numbers according to it types we will be getting the behavior of numbers .
    say for example we can have many questions on Prime numbers.
    number missing questions will all come under Whole or Natural numbers.
    If we go for complex numbers we will have complex multiplication and division which is a bit tough one .
    i expected that we can discuss some easier methods on this!!!

    😎😎
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  • Raviteja.g

    MemberMar 24, 2009

    crazyboy
    tan a = (sin a/cos a)
    Sin 2 = Cos 88
    similarly cos 2 = sin 88
    So [(tan 2)(tan 4)(tan 6)....(tan 86)(tan 88)] = 1
    and Log 1 = 0, so answer is a)

    Correct me if I am wrong?

    -Crazy
    this is also right.
    but i did it in another way as below:
    we all know that
    tanAtanB = 1-(tanA+tan B)/tan(A+B)
    Putting A = 2 and B= 88

    tan2tan88 = 1-(tan2+tan88)/tan 90 = 1-0 =1(tan 90 = infinity)
    we get 1 for all the pairs and we are left with tan 45 with no pair.

    Now tan 45 = 1

    so it comes down to log(1.1.1...) = log 1 = 0.
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  • Raviteja.g

    MemberMar 24, 2009

    again one more question to solve.
    Q) a, b, c are positive integers forming an increasing geometric sequence, b-a is a square, and (loga + logb + logc)/log6 = 6. Then a + b + c is
    (a) 54
    (b) 78
    (c) 111
    (d) 36
    e) None of these
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  • Anil Jain

    MemberMar 24, 2009

    Raviteja.g
    again one more question to solve.
    Q) a, b, c are positive integers forming an increasing geometric sequence, b-a is a square, and (loga + logb + logc)/log6 = 6. Then a + b + c is
    (a) 54
    (b) 78
    (c) 111
    (d) 36
    e) None of these
    (Log (abc) / Log abc) = 6

    so we got take 36 as one of the terms .. then.. we can take the other terms. 6^4.. so we know 27*48 .. =6^4.. answer is c.

    so answer is 27, 36, 48 = 111

    -Crazy
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  • Raviteja.g

    MemberMar 24, 2009

    (Log (abc) / Log abc) = 6
    i can't get you crazyboy
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  • Anil Jain

    MemberMar 24, 2009

    Raviteja.g
    i can't get you crazyboy
    Ok Let me explain in detail...

    = Log a + log b + log c
    = Log abc

    so on the same principle
    6=(loga + logb + logc)/log 6
    6=log (abc)/log 6

    abc are in GP so b^2 = ac
    log (b^3) = 6 (log 6)
    log (b^3) = log (6^6)
    b^3 = 6^6
    b = 36

    I hope i am suounding much better now...

    -Crazy
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  • Raviteja.g

    MemberMar 24, 2009

    ya. I got it
    and its correct and the way i did is
    log a + log b + log c = 6 log 6--------(1)
    a,b,c are in GP. so b^2 = ac => 2 log b = log a + log c------(2)

    from 1 and 2, we get
    3 log b = 6 log 6 => b = 36

    As (b - a) is a square, a can be 32, 27, 20, 11. Among these only for a = 27, we can have an integral value for c which is 48.

    hene a+b+c+ = 27+36+48 = 111. so option c....
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  • Anil Jain

    MemberMar 24, 2009

    Raviteja.g
    ya. I got it
    and its correct and the way i did is
    log a + log b + log c = 6 log 6--------(1)
    a,b,c are in GP. so b^2 = ac => 2 log b = log a + log c------(2)

    from 1 and 2, we get
    3 log b = 6 log 6 => b = 36

    As (b - a) is a square, a can be 32, 27, 20, 11. Among these only for a = 27, we can have an integral value for c which is 48.

    hene a+b+c+ = 27+36+48 = 111. so option c....
    Sorry to say but if you think the way I have solved the question is not a correct way 😁 then give a serious thoughts about your math skills.

    CAT is all about how quickly you can solve the question. Its nothing like by proper method you can solve it or not.

    No offense means!!

    -Crazy
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  • Raviteja.g

    MemberMar 25, 2009

    CAT is all about how quickly you can solve the question. Its nothing like by proper method you can solve it or not.
    yes you are correct.
    but here it didn't seem that the paths you solved the problems are time taking.
    and I think the above problems are not up to the mark for testing of fastness. Right?
    so ,don't worry.
    what makes you to think in that way?
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  • Anil Jain

    MemberMar 25, 2009

    Raviteja.g
    yes you are correct.
    but here it didn't seem that the paths you solved the problems are time taking.
    and I think the above problems are not up to the mark for testing of fastness. Right?
    so ,don't worry.
    what makes you to think in that way?
    Absolutely correct, even I didnt say/think that somebody is testing speed of somebody.

    I was just saying that you should not comment that which is the right method. You solved it by your method and I solved it by my method.

    -Crazy
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  • Saandeep Sreerambatla

    MemberMar 25, 2009

    All are correct 😁.
    So please guys post questions and answers its interesting.
    Dont argue even friendly argument also a big NO .
    i argued earlier and i am sorry about it.
    so we will continue with questions.
    😎
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  • Raviteja.g

    MemberMar 30, 2009

    Here i poses a simple question.
    Find the sum till n terms of the series where T(n)= 2^(n-1) × (2^n- 1) ?

    its very easy.
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  • Raviteja.g

    MemberApr 7, 2009

    Hey this thread again went dead
    Crazyboy i think you can solve this problem
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  • Saandeep Sreerambatla

    MemberMay 21, 2009

    Few tips to solve the problems based on series.
    The questions will be mostly on these types::
    For Finding missed or next number in the series The series may in the form of,
    Even Numbers,Odd Numbers,Composite Numbers,Prime Numbers,Multiplyers ,Divisors,
    In the form of Arithmatic Progession, or In the form of Geometric Progression,
    Succssively divided by 8,6,4,2 like that,
    Addition of the consecutive numbers,
    Subtraction of the consecutive numbers,
    Multiplication of the consecutive numbers,
    Division of the consecutive numbers,
    Consecutively Adding or Subtracting or Multiplying orDividing by Even numbers or Odd numbers or prime numbers,
    Square series ,cube series
    Square+1 or -1
    Square+2 or -2 or *2 or/2
    Square+3 or-3 or *3 or /3Like that or
    Cube+1 or -1
    Cube+2 or -2 or *2 or /2
    Cube+3 or -3 or *3 or /3 Like that
    Middle number is addition or subtraction or multiplication or division of the other two numbers
    Sometimes starts with two series you can guess and
    Add any number to first number subtract any number from second number
    Multiply any number to first number divide the second number with any number
    Some time here you can do in the reverse format also
    Every number multiplied by (.5 or1.5)
    Every number divided by(.5or1.5)
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  • Saandeep Sreerambatla

    MemberMay 22, 2009

    Here is an interesting question.

    All of us know 4! = 24

    What is the value of 4!! and 4!!!
    anyone??
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  • silverscorpion

    MemberMay 22, 2009

    I don't get it buddy.

    4!! will be 24! and 4!!! will be 24!! I guess..
    I don't know how to go about it..
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  • Saandeep Sreerambatla

    MemberMay 22, 2009

    Any takers ??

    i have read in some site , i too wondered by seeing this answer,
    i dont know the explanation but the answer is ..

    4!! = 4 * 2 = 8

    The difference is 2 here, so if you want 7!! = 7 * 5 * 3 * 1

    4!!! = 4* 1 = 4

    For 7!!! here = 7 * 4 * 1

    I guess it should be useful for everyone here..
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  • silverscorpion

    MemberMay 23, 2009

    oh, is this the meaning of the notation?? I missed that.

    I guess 24! would be (4!)! and not 4!!. Right??

    Anyhow, nice one ES.
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  • h.roopesh

    MemberMay 23, 2009

    Its d infinity
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  • Saandeep Sreerambatla

    MemberMay 24, 2009

    Yes 24! is (4!) ! not 4!!

    I am not sure why the answer is like this ? need to refer some books or some sites , anyone with clear explanation is expected here.
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  • shalini_goel14

    MemberMay 24, 2009

    English-Scared
    Any takers ??

    i have read in some site , i too wondered by seeing this answer,
    i dont know the explanation but the answer is ..

    4!! = 4 * 2 = 8

    The difference is 2 here, so if you want 7!! = 7 * 5 * 3 * 1

    4!!! = 4* 1 = 4

    For 7!!! here = 7 * 4 * 1

    I guess it should be useful for everyone here..
    I am just guessing one explanation from my side. 😕

    If number of factorials sign is more than or equal to one then subtract the count from the previous number and keep on repeating and multiplying until you get it zero.

    Ex
    4! = 4 * 3 [(4-1=3) as 1 factorial sign is there ] * 2 [3-1=2 ] * 1 [2-1]
    4!! = 4 * 2 [(4-2=2)as 2 factorial signs are there]
    4!!! = 4 * 1 [(4-3=1)as 3 factorial signs are there]
    7!! = 7 * 5 [(7- 2=5 ) as 2 factorial signs are there ] * 3 [ 5-2=3 ] * [3-2=1]
    7 !!! = 7 * 4 [(7- 3=4 ) as 3 factorial signs are there ] * 1 [ 4-3=1 ]
    Unfortunately my stupid trick is working for your provided cases somehow. Any corrections to my logic, Most Welcome 😀
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  • Saandeep Sreerambatla

    MemberMay 24, 2009

    I too thought of the same procedure.
    I guess we need to investigate more on what is Factorial ?
    Will post here if i get any solution , though i too agree with shalini's solution as it gives proper answer to all the factorials.

    IF any one has a proper solution please post here.

    Thanks Everyone!!
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