Consider a group comprising of 4 students- A, B, C and D, who along with other students stand in a row. A and B stand in sixth and seventh positions, respectively from the left. C and D stand in the fourth and fifth positions, respectively from the right. When B and C exchange their positions, then B will be 15th from the left.
With reference to the information given above, which of the following statements are correct?
(A) D's position from the left is 16th.
(B) A's position from the right is 13th.
(C) C's position from the right is 12th, after exchange.
(D) If A and D also exchange their positions between themselves, then D's position from the left is 6th.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → (B), (C) and (D) only
For anyone in a row, position from the left + position from the right = total + 1. The exchange gives the total:
After the exchange B stands where C stood, so C was 15th from the left.
C is also 4th from the right, so the total is \(15+4-1=18\).
D is 5th from the right, so D is \(18+1-5=14\)th from the left.
(A) D’s position from the left is 16th. Incorrect. D is 14th from the left, just before C.
(B) A’s position from the right is 13th. Correct. A is 6th from the left, so from the right A is \(18+1-6=\) 13th.
(C) C’s position from the right is 12th, after exchange. Correct. After the exchange C takes B’s place, 7th from the left, so from the right C is \(18+1-7=\) 12th.
(D) If A and D also exchange their positions between themselves, then D’s position from the left is 6th. Correct. D moves into A’s place, 6th from the left.