mrunal [aptitude] family trees & blood relations_ logical arrangement made easy » mrunal

[Aptitude] Family Trees & Blood Relations: Logical Arrangement Made Easy

Introduction1.Dataset #1

Step 1: Gender and Generation table

Step 2: Checklist

Questions based on the Family-Data

2.

Dataset #2: UPSC CSP2000

Step #1: Gender and Generation table

Step-2: Run the checklist

Step-3: Solve the Question

3.

Do eliminate wrong options4.Keep a Watch on the Watch5.Previous Articles on Aptitude6.

Introduction

Family relation / Family tree / Bloodline related aptitude questions are prettycommon in CSAT, CMAT, IBPS and CAT.

Lets try a very clichd and easy question.

Dataset #1

There are 6 members in a family: A to F. There are two married couples, D isgrandmother of A and mother of B, C is the wife of B and mother of F, F is thegranddaughter of E.Just like our Prime Minister, There is no dum in this sum. It requires only three simplesteps.

Step 1: Gender and Generation table

The data talks about three things: Gender (M/F), Generation(1/2/3) and BloodRelations (mom-son etc.)If you try to arrange all three of them simultaneously, itll only lead to frustrationand wastage of time. So first concentrate on two items only: Gender andGeneration. The Relations will fall in line by themselves.

Given data: D is grandmother of A and mother ..So D is the oldest Generation and she is definitely female.But we dont know whether A is male / female.

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Anyways fill up the Gender Generation table

Generation Male Female Not sure(M/F)

1 Oldest D

2 Mid aged

3 Youngest A

Given data: D is grandmother of A and mother of B

Obviously B falls in the 2nd generation (mid-aged) but still we dont know the genderof B.


1 Oldest D

2 Mid aged B

3 Youngest A

Given data: C is the wife of B and mother of FThis one statement, tells us three things

C is a female and mid-aged (2nd generation)B is a male.

F is 3rd generation. But we dont know the Gender of F

Update the table with this new information


1 Oldest D

2 Mid aged B C

3 Youngest A,F

Given data: F is the granddaughter of EThis tells us following

F is a female.

F is 3rd generation (although we knew it already.)

E is 1st generation and since D was female, this has to be male (Granddaddy).

Update the table


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1 Oldest E D

2 Mid aged B C

3 Youngest F* A

*intentional mistake.

Step 2: Checklist

In the arrangement questions: whether it is circular arrangement, lineararrangement or family tree: always runs the checklist after youre done arrangingthe items.If you had made any mistake in the arrangement, youll find it out at step2.IF you proceed directly to solving questions, it may happen that youll get allanswers incorrect. Because in aptitude tests, they design the 4 answers options(a/b/c/d) in such a way that even if you got incorrect arrangement, youll findanswers matching to your arrangement!

So here is our final table


1 Oldest E D

2 Mid aged B C

3 Youngest F A

And here is our checklist from the given question data

Checklist Pass/Fail

There are two married couples Pass

D is grandmother of A and mother of B Pass

C is the wife of B and mother of F Pass

F is the granddaughter of E. #EPICFAIL

Red light. STOP. Checklist item #4 is giving FailHaha see? I had made a stupid mistake in the table (intentionally).F is granddaughter of E but I had mistakenly put F in the Male column.In the actual exam, under the stress, many people make such silly-mistakes.They calculate the sum correctly in their head but on the paper, their hand writesa different thing altogether.


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Ofcourse in the actual exam, there is time-limit, so you cant do crossverification/checklist in each and every aptitude question.But in the arrangement questions- each dataset comes with 4-5 questions. So,even one silly-mistake will cost you four times the negative marks. Therefore itsalways a good idea to run checklist on arrangement questions.Our final correct table looks like this


1 Oldest E D

2 Mid aged B C

3 Youngest F A

If you want to construct a family tree, itll look like following

Greenlight. Proceed further. Time for some Questions.

Questions based on the Family-Data

Q1.Who among the following is one of the couples?

CDDEEBCannot be determinedNone of these

well look at the table


1 Oldest E D

2 Mid aged B C

3 Youngest F A


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There are two couples : ED and BCFinal answer: (b) DE is one of the couple.

Q2. Which of the following is definitely false?

a) A is brother of Fb) A is sister of Fc) D has two grandsonsd) Cannot be determined

From the table


1 Oldest E D

2 Mid aged B C

3 Youngest F A

We are not sure about As gender. A can be brother OR sister of F.So option (a) and (b) are eliminated. We cannot definitely say which of them is false.But checkout the third option (c), it says D has two grandsonsNow this is definitely false because we know for sure that granddaughter F is afemale. So Grandma D cannot have two grandsons in any case.Final answer: (c)

Q3. How many female members are there in the family?

234Cannot be determinedNone of these.

Since we dont know the gender of A, we cannot determine the number of males andfemales in this family.Answer: Cannot be determined.

Anyways that was quite an easy dataset. Lets try something a bit complicated.

Dataset #2: UPSC CSP2000

There are 6 people in a family: A to F

Men and women are in equal numberA and E are sons of FD is the mother of two: one boy and one girl


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B is the son of AThere is one married couple in the family at present.

Step #1: Gender and Generation table

Given: Men and women are in equal number

Obviosuly, this means the family has 3 men and 3 women. How else do you distribute 6into equal numbers otherwise!Given: A and E are sons of FIt tells us three things

A and E are males

F is one generation higher than A,E. It means F is definitely not in the 3rd

(youngest) Generation.But no exact idea about gender or generation of F.


1 Oldest

2 Mid aged

3 Youngest

0 (Not Sure) A,E (2/3) F(1/2)

^Notice this time Ive also made an extra row 0(Not sure) to accommodate A and E.

The (2/3) suggests that A and E can be either 2nd or third generation.Given: D is the mother of two: one boy and one girlIt tells us two things

D is female

D is not the youngest (3rd)generation, because she has kids. Thus She falls either

in 1st or in 2nd generation.

Update the table


1 Oldest

2 Mid aged

3 Youngest


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0 (Not Sure) A,E (2/3) D(1/2) F(1/2)

Given: B is the son of ATells us many things

B is male. Because opening statement of the dataset said equal number of menand women and Since A,E and B are sons (males) therefore C,D and F arefemales. C is a female but we dont know her generation: 1/2/3.

We already know that A+E are sons of F. Therefore A cannot be in 1st

generation. (warnaa uski Maa F kidhar jaayegi?)

It means A is definitely 2nd generation male. Because A cannot be 3rd generation(warnaa uskaa Betaa B kidhar jayegaa?)And Since A is second generation, his brother F is also second generation.Since A+F are in second generation, their mother F has to be first generation.

Update the table with this information


1 Oldest F

2 Mid aged A,E

3 Youngest B

0 (Not Sure)D(1/2)C(1/2/3)

Atleast now we know who is male and who is female. But there is one problem: Wedont know exact generations of female C and D.Given: D is the mother of two: one boy and one girlAssume that mom D is first generation. But we already know the there are only threemales in this family.

A+E= second generation but sons of FB is son of daddy A

So we cant put D is first generation (otherwise 2nd generation mein Tisraa BetaaKidhar Se Laaoge?)It means D is definitely second generation female. And corollary to that, C is thirdgeneration female and daughter of mommy D. This satisfies the conditionD is the mother of two: one boy(B)and one girl(C)Update the table


1 Oldest Dead F


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2 Mid aged A,E D

3 Youngest B C

0 (Not Sure)

Only one problem remains: Who is the husband of D: is it A or is it E?Given: There is one married couple in the family at present.Given: B is the Son of A.From previous steps we already Concluded that: D is mother of B+CFrom these three sentences we can derive that B is the son of A+D , therefore A+D arehusband and wife.And As brother E is middle-aged unmarried clown just like Patrakaar Popatlaalbecause of his arrogant and obnoxious attitude, no woman is interested in marrying withhim.anyways, Im drawing this family tree from Grandson Bs point of view.

Step-2: Run the checklist

Checklist Pass/Fail?

Men and women are in equal number Pass: 3+3

A and E are sons of F Pass

D is the mother of two: one boy and one girl Pass

B is the son of A Pass

Green light. Go on, solve the questions.

Step-3: Solve the Question

Which of the following inference can be derived from the given dataset?

i) A,B and C are femalesii) A is the husband of Diii) D is the grandmother of Fiv) E and F are children of D


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From the family tree diagram, we can see that option (ii) is correct: A is indeed thehusband of D.

Do eliminate wrong options

In some arrangement questions Two cases / two tables/Two family treesmay be possible.So even after passing the checklist, you may still get incorrect answer; becausewhile doing the arrangement you might have missed some minor detail so youconcentrated only on one possible case. You cannot rectify this mistake withchecklist alone, because checklist will pass for each of Two possible cases. (Forexample recall the circular arrangement/round table sitting case in previous article.)Therefore, when youre checking the 4 answer options, even if you get correctmatch in second option(ii), dont stop just yet, you should still check whether theremaining answer option 1, 3 and 4 are incorrect or not.

Answer statementsTrue /False

Why?

A,B and C arefemales

FalseDataset itself said A+E are sons of F. So Acant be a female.

A is the husband of D True Table says so.

D is the grandmotherof F

False Table says F is saas and D is her bahu.

E and F are childrenof D

FalseA+E are the sons of F, it is given in the questionitself!So E and F cannot be children of D!

Final answer: A is the husband of D.

Keep a Watch on the Watch

As I had said earlier,Out of their lack of interest, inferiority complex, many aspirants dont practice enoughaptitude sums at home.So in the actual exam, they get stuck in 7/10 math questions = stress.While under stress, they come across the logical-arrangement questions. They startthinking like a defeated gambler:I can definitely solve this arrangement; beside i couldnot tick previous 7 questionsso I must solve this anyhow, no matter how much time it takes!Problem: They end up wasting good 15-20 minutes in one dataset only. Sometimeseven after investing 20 minutes in one arrangement, they may not get the final answerbecause they did not practice enough sums at home. Thats why


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Practice maximum questions at Home.In the examhall, always keep a watch on your wristwatch. Learn to give up thefight before its too late and invest that time in the remaining questions in othersections.And most importantly: Dont hate the Aptitude/Maths.Competition is tough everywhere: whether youre an aspirant ofCSAT/CMAT/IBPS or CAT, so if you dont work hard, someone else will, andthen hell get the job/admission.So dont hate the aptitude, hate your own laziness and fix it before its too late.With constant practice, anyone from arts, commerce and science can masteraptitude.

URL to article: http://mrunal.org/2012/04/aptitude-family-trees-blood-relations.html

Posted By Mrunal On 30/04/2012 @ 17:54 In the category Aptitude


10 of 10 7/28/2014 6:50 PM

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