Skip to main contentSkip to solution

A, B, C, D, L, M, N and O live on eight different floors of the same building. The lowermost floor in the building is numbered 1, the floor above it, number 2 and so on till the topmost floor is numbered 8.

L lives on the fourth floor. Sum of floor numbers of L and C is more than 10. The sum of floor numbers of D and O is 8. O does not live on an odd numbered floor. M lives on an odd numbered floor. The sum of floor numbers of M and D is more than 12. More than three people live between M and N. The sum of floor numbers of N and A is more than 5.

Which of the following is NOT TRUE based on the given information?

Solution

✅ Correct Option: 4

Step 1: Analyze Fixed Information & Basic Constraints

  • L is on floor 4.
  • O is on an even floor (2,6,82, 6, 8).
  • M is on an odd floor (1,3,5,71, 3, 5, 7).

Step 2: Determine positions of D, O, and M

  • Constraint: Sum of floors of D+O=8D + O = 8.
    • Since O is even (2,6,82, 6, 8) and L is already on 4:
    • If O=8O=8, then D=0D=0 (Impossible).
    • If O=6O=6, then D=2D=2.
    • If O=2O=2, then D=6D=6.
  • Constraint: Sum of floors of M+D>12M + D > 12.
    • If D=2D=2, then M+2>12⇒M>10M + 2 > 12 \Rightarrow M > 10 (Impossible).
    • Therefore, D must be 6 and O must be 2.
    • With D=6D=6, M+6>12⇒M>6M + 6 > 12 \Rightarrow M > 6. Since M is odd, M is on floor 7.

Step 3: Determine positions of C and N

  • Constraint: Sum of floors of L+C>10L + C > 10.
    • L=4L=4, so 4+C>10⇒C>64 + C > 10 \Rightarrow C > 6.
    • Floors >6>6 are 7 and 8. Since M is on 7, C is on floor 8.
  • Constraint: More than 3 people live between M and N.
    • M is on 7. The gap must be at least 4 floors (6,5,4,36, 5, 4, 3).
    • This forces N to be below floor 3. Floor 2 is O, so N is on floor 1.

Step 4: Determine positions of A and B

  • Constraint: Sum of floors of N+A>5N + A > 5.
    • N=1N=1, so 1+A>5⇒A>41 + A > 5 \Rightarrow A > 4.
    • Available floors are 3 and 5. Since A must be >4>4, A is on floor 5.
  • Remaining: The only empty spot is floor 3, so B is on floor 3.

Final Arrangement Table

FloorPerson
8C
7M
6D
5A
4L
3B
2O
1N

Verifying the Options

  • A) A lives on a floor immediately above L: True (55 is above 44).
  • B) Only four people live between M and O: True (Floors 6, 5, 4, 3 are between 7 and 2).
  • C) C lives on the topmost floor: True (Floor 8).
  • D) B lives on floor number 5: FALSE. (B lives on floor 3; A lives on floor 5).

Correct Answer: Option D

Keyboard Shortcuts

  • Left arrow: Previous question
  • Right arrow: Next question
  • S key: Jump to solution
  • Q key: Jump to question