Difficulty: Medium
Correct Answer: 75
Explanation:
Introduction / Context:
This combines two-sided rank within the passed subgroup with an overall pass:fail ratio to determine total class size.
Given Data / Assumptions:
Concept / Approach:
First, compute the number of passed students (P) using Kalyan’s two-sided rank: P = 27 + 34 − 1. Then use the given ratio to get total N.
Step-by-Step Solution:
P = 27 + 34 − 1 = 60.Pass:Fail = 4:1 → P = 4k ⇒ 60 = 4k ⇒ k = 15.Total N = 5k = 75.
Verification / Alternative check:
Failed students = N − P = 75 − 60 = 15, matching the 4:1 ratio.
Why Other Options Are Wrong:
60 is the passed count, not total; 90 contradicts the computed ratio; “Data inadequate” is incorrect because the subgroup data suffices.
Common Pitfalls:
Using Neeta’s rank to compute P; forgetting to subtract one in two-sided ranks.
Final Answer:
75
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