Eight friends, A, D, H, I, K, N, S and U are seated in a circle facing the centre. S is between H and U. K is third to the left of I. A is between N and I. U is third to the right of D. Which of the following must be true?
(A) N is seated next to K.
(B) U is seated next to D.
(C) I is seated next to D.
(D) A is seated third to the right of S.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → (A) and (C) only
All eight face the centre, so each person’s left is clockwise and right is anticlockwise. Number the seats 1 to 8 clockwise, starting with I in seat 1.
K is third to the left of I, so K is three seats clockwise from I: K in seat 4.
A is between N and I, so A sits next to I: either A in seat 2 with N in seat 3, or A in seat 8 with N in seat 7.
Take A in 8 and N in 7:
U is third to the right of D, so U is three seats anticlockwise from D: D 5 and U 2, or D 6 and U 3.
S must sit next to U with H on its other side.
With U in 2, S takes seat 3 and the seat beyond it is K’s; with U in 3, S takes seat 2 and the seat beyond it is I’s.
H has no seat, so this case fails.
So A is in seat 2 and N in seat 3:
Seats 5 to 8 are left.
The only pair with U three seats anticlockwise from D is D in seat 8, U in seat 5.
S is between H and U: S in seat 6, H in seat 7.
(A) N is seated next to K. Correct. N (seat 3) and K (seat 4) sit side by side.
(B) U is seated next to D. Incorrect. U’s neighbours are K and S; D sits between H and I.
(C) I is seated next to D. Correct. D (seat 8) and I (seat 1) sit side by side.
(D) A is seated third to the right of S. Incorrect. Going anticlockwise (to S’s right) from S: U, K, N, so N is third to the right of S; A is fourth.