Practice Questions
Concept Explanation
Rank problems find position from left/right or count persons between positions. Total = left rank + right rank − 1.
Key Formulas
- Total persons = L + R − 1 (L = rank from left, R = rank from right)
- Persons between two at ranks a and b = |a − b| − 1
- Arrangements with fixed positions use nPr on remaining slots
Example
Rank 5 from left and 8 from right in a line: total = 5 + 8 − 1 = 12.
Common Trap
Do not add left and right ranks directly; subtract 1 for double counting the person.
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Q1 Easy
Rank 5 from left and 8 from right in a line. Total persons?
Explanation5 + 8 − 1 = 12. -
Q2 Easy
Rank 7 from left and 5 from right. Total persons?
Explanation7 + 5 − 1 = 11. -
Q3 Medium
In a row of 15, rank from right of person at 6th from left?
ExplanationRight rank = 15 − 6 + 1 = 10. -
Q4 Medium
Persons between ranks 4 and 9 from left in same row?
Explanation|9 − 4| − 1 = 4. -
Q5 Easy
Rank 3 from left and 10 from right. Total persons?
Explanation3 + 10 − 1 = 12. -
Q6 Medium
In a row of 20, 8th from left is how many from right?
Explanation20 − 8 + 1 = 13. -
Q7 Hard
Rank 12 from left and 12 from right. Total persons?
Explanation12 + 12 − 1 = 23.
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Q8 Medium
Persons between 5th from left and 5th from right in a row of 11?
Explanation5th from right is 7th from left. Between 5 and 7: 1 person. -
Q9 Medium
6 people sit in a row. A is 2nd from left, B is 3rd from right. Persons between A and B?
ExplanationA at 2, B at 4 (6−3+1). Between: 4−2−1 = 1. -
Q10 Easy
Rank 1 from left and 18 from right. Total persons?
Explanation1 + 18 − 1 = 18. -
Q11 Medium
In a row of 25, rank from left of person 10th from right?
Explanation25 − 10 + 1 = 16. -
Q12 Hard
Rank 9 from left equals rank 9 from right. Total persons?
Explanation2 × 9 − 1 = 17. -
Q13 Easy
Persons between ranks 2 and 8 from left?
Explanation8 − 2 − 1 = 5. -
Q14 Easy
Rank 4 from left and 6 from right. Total persons?
Explanation4 + 6 − 1 = 9.
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DS1 Easy
What is the total number of persons in the row?
Statement IA person is 5th from the left.
Statement IIThe same person is 8th from the right.
ExplanationNeed both: 5 + 8 − 1 = 12. -
DS2 Medium
What is the rank from the right?
Statement IThere are 15 persons in a row.
Statement IIA person is 6th from the left.
ExplanationNeed both: 15 − 6 + 1 = 10.
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DS3 Easy
How many persons sit between two positions?
Statement IOne person is 4th from the left.
Statement IIAnother is 9th from the left.
ExplanationStatement I alone with II: |9 − 4| − 1 = 4. -
DS4 Medium
Is the total number of persons greater than 20?
Statement IRank from left is 11.
Statement IIRank from right is 11.
ExplanationEach alone insufficient. Together: 11 + 11 − 1 = 21 > 20.