Read the information to answer the given question.
P, Q, R and S are to be seated in a row. But R and S cannot be together. Also, Q cannot be at the third place from the left end.
Which of the following must be false?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → P is at the first place from left end
A statement that must be false is false in every arrangement that obeys both conditions, so all the allowed arrangements are listed first. R and S may not sit side by side, so in a row of four their places can only be 1 and 3, 1 and 4, or 2 and 4.
R and S at places 1 and 3: P and Q take places 2 and 4 in either order, so P is 2nd or 4th
R and S at places 1 and 4: places 2 and 3 are left; Q cannot be 3rd, so Q is 2nd and P is 3rd
R and S at places 2 and 4: places 1 and 3 are left; Q cannot be 3rd, so Q is 1st and P is 3rd
P can be 2nd, 3rd or 4th, but in no arrangement is P 1st: place 1 always goes to R, S or Q. So “P is at the first place” must be false, while the other three options are possible.