GATE Mechanical 2017 Set 2 | GA | Question: 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

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?

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because the answer is some in every case. Answer can only be 1.

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