College of Admission Tests Multan

Placement Arrangements

Solve the question of and select the option from the choices A through D/E. Check your Answer and view the explanation.

Four couples—J, K, L, M—are standing in a line. Their positions are numbered consecutively from 1 to 8, and each person is holding hands with the persons on either side of him or her.

J and J are holding hands.

K and K are not holding hands.

L and L are holding hands.

One of the Ls is at one end of the line, and one of the Ms is at the other end.

Question: 5

Which one of the following must be true?
  • At least one J is holding hands with a K.
  • At least one L is holding hands with a J.
  • At least one L is holding hands with a K.
  • At least one M is holding hands with an L.
  • At least one J is holding hands with an M.

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Correct Answer: A

The conditions “J and J are holding hands” and “L and L are holding hands” are naturally symbolized as JJ and LL, respectively. The condition “K and K are not holding hands” can be symbolized as K...K. [The symbol ~(KK) would also work well, but the symbol K...K is more descriptive because it shows the space between the Ks.] The condition “One of the Ls is at one end of the line, and one of the Ms is at the other end” can be symbolized as L=1st/last and M=1st/last. The diagram will consist of eight dashed lines numbered 1 through 8, from left to right:

JJ

LL

K ... K

L = First / Last

M = First / Last

1to8line -27320368

No significant conditions can be derived from the given information, and no conditions can be placed on the diagram. So we attack the questions.

We will consider only the diagram with M at the left end and the Ls at the right end. The diagram with the Ls at the left end and the M at the right end is the mirror image, so it will generate the same answer. There are four possible diagrams, one for each of the four possible positions of the condition JJ:

51arrangementq -77521104

From the condition K...K, we see that in the first diagram there must be a K in position 4, in the second diagram there must be a K in position 2, in the third diagram there must be a K in position 6, and in the last diagram there must be a K in position 4:

52arrangementq -91271648

Each of these diagrams has a J next to a K. In other words, at least one J must be holding hands with a K. Hence the answer is (A).