Rows — In a row of 50 students, how many are between Suresh and Mohan? Statements: I. Suresh is 12th from the left end; Mohan is 17th from the right end. II. Suresh is six places away from Jayesh, who is 20th from the left end.
Verbal Reasoning
Data Sufficiency
Difficulty: Easy
Choose an option
Answer
Correct Answer: Statement I alone is sufficient; Statement II alone is not sufficient.
Explanation
Introduction / Context:We must compute the number of students strictly between two given positions in a fixed-size row.
Given Data / Assumptions:
- Total = 50 students.
- I: Suresh = 12th from left; Mohan = 17th from right.
- II: Suresh is 6 away from Jayesh (20th from left).
Concept / Approach:Convert Mohan's right-based rank to a left-based rank; then apply the between formula: |p−q| − 1.
Step-by-Step Solution:
From I: Mohan's left-rank = 50 − 17 + 1 = 34.Between count = 34 − 12 − 1 = 21.From II alone: Suresh's position is either 14th or 26th; without Mohan's absolute rank, the between count is indeterminate.Verification / Alternative check:Positions are valid within bounds [1,50].
Why Other Options Are Wrong:
- B/C/D/E: II lacks Mohan’s absolute position; I already yields a unique number.
Common Pitfalls:Forgetting the +1 when converting right-to-left rank; forgetting to subtract 1 for exclusivity.
Final Answer:A — Statement I alone suffices (21 students between them).