Eight persons L, M, N, O, P, Q, R and S work on different designations in a company i.e., MD, COO, CEO, CFO, CTO, CMO, Manager and HR. The order of seniority is same as given i.e., MD is the senior-most designation and HR is the junior-most designation.

Three persons are there between S and L. L works below CMO. N is junior to MD but senior to S. More than three persons work between N and P. Same number of persons are junior to P and senior to M respectively. R is senior to CMO but junior to Q.

How many persons are junior to R?

Correct Answer: Three

Let us analyze the given information step-by-step to determine the exact designation and arrangement of all eight persons.

The designations in decreasing order of seniority (from senior-most to junior-most) are:
1. MD
2. COO
3. CEO
4. CFO
5. CTO
6. CMO
7. Manager
8. HR

Let us break down the clues:

1. "L works below CMO."
Since CMO is at rank 6, L must be either Manager (rank 7) or HR (rank 8).

2. "Three persons are there between S and L."
- Case A: If L is HR (rank 8), then counting 3 positions up (ranks 7, 6, 5), S must be CFO (rank 4).
- Case B: If L is Manager (rank 7), then counting 3 positions up (ranks 6, 5, 4), S must be CEO (rank 3).

3. "N is junior to MD but senior to S."
- MD is rank 1. So N must be higher in rank than S, but lower than MD (i.e. between rank 2 and rank of S).

4. "More than three persons work between N and P."
This means there are at least 4 persons between N and P (difference in rank position is at least 5).

5. "Same number of persons are junior to P and senior to M respectively."
This means if P is at rank k from the top (1-indexed), M is at rank k from the bottom (i.e. rank 9 - k), or vice versa depending on positioning.

6. "R is senior to CMO but junior to Q."
CMO is rank 6. So R must be senior to CMO (ranks 1 to 5). Since R is junior to Q, Q must be senior to R (Q is above R).

Now let us test the cases:

Testing Case A (L = HR [rank 8], S = CFO [rank 4]):
- S is at rank 4.
- N is senior to S (rank 4) and junior to MD (rank 1), so N can be rank 2 (COO) or rank 3 (CEO).
- If N is rank 2 (COO): More than 3 persons between N and P means P must be at rank 7 (Manager) or rank 8 (HR). Since L is HR (rank 8), P must be Manager (rank 7).
- Checking P = rank 7 (Manager): There is 1 person junior to P (HR). Thus, 1 person must be senior to M, which means M is at rank 2 (COO). But N is already at rank 2! So N cannot be rank 2.
- If N is rank 3 (CEO): More than 3 persons between N and P means P must be at rank 8 (HR), but L is already HR. So this case is invalid.

Testing Case B (L = Manager [rank 7], S = CEO [rank 3]):
- S is at rank 3.
- N is senior to S (rank 3) and junior to MD (rank 1), so N MUST be rank 2 (COO).
- Since N is at rank 2, to have more than 3 persons between N and P, P must be at rank 7 or rank 8. Since L is at rank 7 (Manager), P MUST be rank 8 (HR).
- Since P is at rank 8 (HR), 0 persons are junior to P. Therefore, 0 persons are senior to M, which means M MUST be rank 1 (MD).
- Now we have placed:
Rank 1: M
Rank 2: N
Rank 3: S
Rank 7: L
Rank 8: P
- The remaining vacant designations are ranks 4 (CFO), 5 (CTO), and 6 (CMO).
- The remaining persons to place are Q, R, and O.
- We know "R is senior to CMO (rank 6) but junior to Q".
- So R cannot be rank 6. Thus, R can be rank 4 or rank 5.
- Since Q is senior to R, Q must be above R. Therefore, Q = rank 4 (CFO) and R = rank 5 (CTO).
- The remaining person O takes rank 6 (CMO).

Final Designation Table:
1. MD - M
2. COO - N
3. CEO - S
4. CFO - Q
5. CTO - R
6. CMO - O
7. Manager - L
8. HR - P

Conclusion:
R is designated as CTO (rank 5).
The persons junior to R are CMO (O), Manager (L), and HR (P), which totals 3 persons.