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Aptitude Questions - time and work problems

General/Othereasy0.3 min readPremium

**Formula**: Combined rate = 1/a + 1/b; time = 1/(1/a + 1/b). **Example**: A in 10 days, B in 15. Rates 1/10, 1/15. Together: 1/10 + 1/15 = 5/30 = 1/6. Time = 6 days. **Three workers**: 1/(1/a + 1/b + 1/c). **Pipes**: Fill positive, drain negative....

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Frequency
Low
Asked at 1 company
Category
243
questions in General/Other
Difficulty Split
151E|43M|49H
in this category
Total Bank
1,863
across 7 categories
Asked at these companies
McKinsey
Interview Pro Tip

Pro-Move: Show your work step-by-step; write down rates before calculating. Red Flag: Guessing or skipping steps—interviewers want to see reasoning.

Why This Question Matters

This easy-level General/Other question appears frequently in data engineering interviews at companies like McKinsey. While less common, it tests deeper understanding that distinguishes strong candidates.

How to Approach This

Start by clearly defining the core concept being asked about. Interviewers want to see that you understand the fundamentals before diving into implementation details. Structure your answer with a definition, then explain the practical application with a concise example.

Expert Answer
55 words

Formula: Combined rate = 1/a + 1/b; time = 1/(1/a + 1/b). Example: A in 10 days, B in 15. Rates 1/10, 1/15. Together: 1/10 + 1/15 = 5/30 = 1/6. Time = 6 days. Three workers: 1/(1/a + 1/b + 1/c). Pipes: Fill positive, drain negative. Best practice: Identify rates; add; invert for time.

The complete answer continues with detailed implementation patterns, architectural trade-offs, and production-grade considerations covering performance optimization and real-world examples.

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According to DataEngPrep.tech, this is one of the most frequently asked General/Other interview questions, reported at 1 company. DataEngPrep.tech maintains a curated database of 1,863+ real data engineering interview questions across 7 categories, verified by industry professionals.

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