Difficulty: Medium
Correct Answer: Either I or II is sufficient
Explanation:
Introduction / Context:This DS question asks for P’s bottom rank in a class of 30. Each statement provides relative positioning that may allow a unique absolute rank for P. We check each independently.
Given Data / Assumptions:
Concept / Approach:If there are x students between two ranks r1 and r2, then |r1 − r2| = x + 1. Use this to derive P's top rank and convert to bottom rank by N − r_top + 1.
Step-by-Step Solution:
Using I alone: M is 3rd from the top. With five between M and P, |rank_M − rank_P| = 6. So rank_P could be 3 + 6 = 9 from the top or 3 − 6 which is invalid. Thus rank_P(top) = 9. Hence rank_P(bottom) = 30 − 9 + 1 = 22. I alone is sufficient.Using II alone: K is 4th from the bottom ⇒ from the top K is 30 − 4 + 1 = 27th. With 17 between K and P, |27 − rank_P| = 18 ⇒ rank_P(top) = 27 − 18 = 9 (since 27 + 18 exceeds 30). Thus rank_P(bottom) = 22. II alone is also sufficient.Verification / Alternative check:Both statements independently yield the same unique rank for P (9th from the top, 22nd from the bottom), confirming each suffices.
Why Other Options Are Wrong:
Common Pitfalls:Misinterpreting 'between' (remember to add 1 when converting to rank difference); forgetting to convert bottom to top ranks correctly.
Final Answer:Either I or II is sufficient
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