GATE2017 EC-2: GA-7

Question

Each of $P, Q, R, S, W, X, Y$and $Z$ has been married at most once. $X$ and $Y$ are married and have two children $P$ and $Q. Z$ is the grandfather of the daughter $S$ of $P$. Further, $Z$ and $W$ are married and are parents of $R$. Which one of the following must necessarily be FALSE?

• A. $X$ is the mother-in-law of $R$
• B. $P$ and $R$ are not married to each other
• C. $P$ is a son of $X$ and $Y$
• D. $Q$ cannot be married to $R$

Comments

https://gateoverflow.in/139221/gate-ece-2017

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If Q can be married to R then shall we assume that Z&W can have other children not mentioned in the question?

Because it is clearly mentioned that Z is grandfather of P's daughter. So it is mandatory for P to be married to a child of Z&W.

Please clarify.

Answer 1

Let $\to$ represent the child relation.

• $\{X,Y\} \to P, Q$
• $P \to S$
• $\{Z,W\}\to R$
• Further either $P$ or $P's$ spouse is the child of $Z$ so that $S$ become the grand daughter of $Z.$

1.  $X$ is the mother-in-law of $R$ -- possible if $R$ is married to either $P$ or $Q.$
2. $P$ and $R$ are not married to each other -- $P$ has only $R$ to marry as $Q$ is a sibling and $S$ daughter, but $P$ can also be married to anyone not mentioned in the question. So, this is possible.
3. $P$ is a son of $X$ and $Y$ -- possible as $P$ can either be a son or daughter of $X$ and $Y.$
4. $Q$ cannot be married to $R$ -- FALSE as $Q$ can be married to $R.$ 

Correct Option: D

Comments

 

P can also be married to anyone not mentioned in the question

I think the person cannot be anyone, he/she must be son/daughter of Z and W.

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If Q can be married to R then shall we assume that Z&W can have other children not mentioned in the question?

Because it is clearly mentioned that Z is grandfather of P's daughter. So it is mandatory for P to be married to a child of Z&W.

Please clarify.

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Hear in question clearly mention is that “ Z is the grandfather of the daughter S of P”

final conclusion → p is married (but  P can not married with Q due: both parents are same.)

so,P only married with R .(because No further details is given so we assume that like.)

ANS : P and R Not married to each other is FALSE.