Step 1: Analyze Statement (I) alone.
- There are 8 positions (1=bottom, 8=top).
- "Only three boxes are kept above D" \(\rightarrow\) D is at position 5. (Boxes at 6,7,8 are above).
- "one box is kept between D and Q" and "Q is kept lower than D" \(\rightarrow\) D is at 5, so Q must be at position 3.
- "Q is immediately below P" \(\rightarrow\) P is at position 4.
- From (I), we have the partial stack: __ __ __ P(4) Q(3) __ __. D is at 5. So: __ __ __ D(5) P(4) Q(3) __ __.
- We know the positions of D, P, Q. We don't know the position of R or the box above it. Statement I is not sufficient.
Step 2: Analyze Statement (II) alone.
- "Only one box is kept between A and C" \(\rightarrow\) A __ C or C __ A.
- "C is three boxes above Q" \(\rightarrow\) C is at position x, Q is at x-4. (e.g. C=5, Q=1 or C=8, Q=4).
- "As many boxes are kept above B as are kept below R" \(\rightarrow\) If B is at position n, R is at 9-n. (e.g. B=8, R=1; B=7, R=2 etc.). They are symmetrical.
- This statement gives relative positions but no absolute positions. We cannot locate R. Statement II is not sufficient.
Step 3: Analyze both statements together.
- From (I): D=5, P=4, Q=3.
- Now use (II) with this information: "C is three boxes above Q". Since Q=3, C must be at position 3+4=7.
- Now use "Only one box is kept between A and C". Since C=7, A must be at position 5. But D is at position 5. This creates a contradiction.
Let me re-read "C is three boxes above Q". This means C is at position x, Q is at x-3, or C __ __ Q. No, it means 3 boxes are between them. C __ __ __ Q. So if Q=3, C=7. This seems right.
Let's check the distance. Pos 7, Pos 3. Boxes at 4, 5, 6 are between them. Yes, three boxes. C=7.
"Only one box is kept between A and C". C=7, so A must be at 5 or 9. 9 is not possible. So A=5.
This means A and D are in the same spot (position 5). The statements are contradictory.
Let's re-read "C is kept three boxes above Q". This might mean C is at Q's position + 3 = 3+3=6.
If C=6, then "one box between A and C" means A=4 or A=8. A=4 is not possible as P is there. So A=8.
- So far: A=8, C=6, D=5, P=4, Q=3.
- Positions left: 1, 2, 7. Boxes left: B, R, S.
- Now use "As many boxes above B as below R". Let's test the remaining spots.
- If B=7 (1 above), then R=2 (1 below). This works. S would be at position 1.
- This gives a complete valid arrangement: A(8), B(7), C(6), D(5), P(4), Q(3), R(2), S(1).
- The question is "Which box is kept immediately above R?". In this arrangement, R is at position 2. The box at position 3 is Q.
- Since we have found a unique arrangement and can answer the question, both statements together are sufficient.
How many triangles are there in the figure given below? 