Home » Data Interpretation » Data Sufficiency

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.

Difficulty: Easy

Statement I alone is sufficient; Statement II alone is not sufficient.
Statement II alone is sufficient; Statement I alone is not sufficient.
Either Statement I alone or Statement II alone is sufficient.
Both Statements I and II together are not sufficient.
Both Statements I and II together are sufficient, but neither alone is sufficient.

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.

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.

More Questions from Data Sufficiency

Discussion & Comments