GATE2017 ME-2: GA-5

Question

$P$ looks at $Q$ while $Q$ looks at $R$. $P$ is married, $R$ is not. The number of pairs of people in which a married person is looking at an unmarried person is 

• A. $0$
• B. $1$
• C. $2$
• D. Cannot be determined.

Comments

my query here is that, since we have no information about Q, and also the total number of people otherwise present, how can we definitely say that there is 1 pair of person.

Answer is 1.

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Favourable pair : $(M,UM)$
Two conditions : $Q=$ $\{M,UM\}$

Referring $Q$ condition Favourable pair would be $(Q,R)$ when $Q$ is Married or $(P,Q)$ when $Q$ is unmarried ..

Therefore answer is not dependent on either condition!

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This question really came in a gate paper!! :v

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if Q is  unmarried --->  PQ as a pair

if Q is married -----> QR as a pair

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there is no any information about Q, then how we can make a pair?

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read the question "number of pairs of people in which a married person is looking at an unmarried person"

than you have to assume for Q  for making a couples

ans given is b) 1 right ???

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already there pls refer :https://gateoverflow.in/193486/gate-2017-me2-ga

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Just assume there are only 3 people present then answer is 1 

A better version of this question was asked in TIFR

https://gateoverflow.in/96822/tifr2016-a-1

Answer 1

Two cases possible Either Q is married or Q is unmarried.

If Q is married, $Q$ looking at $R$ counts as 1 required pair.

If Q is unmarried, $P$ looking at $Q$ counts as 1 required pair.

In either cases 1 such pair possible where a married person is looking at an unmarried person.

Correct Answer: $B$

Comments

but they are not asking about the possibilities ..and nowhere in the question words like 

can  or possible are mentioned either..

then how we can determine this?

Answer 2

B option

CASE 1 : When Q is married

QR is the pair.

CASE 2 : When Q is unmarried

PQ is the pair.

Only one of the above case is possible. So number of pairs is 1.

Answer 3

Either Q is married or not it doesn't affect the answer here 

If Q is unmarried then PQ will be a pair and if Q is married then QR will be a pair 

So, the answer is 1

A better version of this question was asked in TIFR

https://gateoverflow.in/96822/tifr2016-a-1