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Quantitative Aptitude
Time and Work
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NTPC Graduate Tier 1 2025 Shift-3 📅 05 Jun, 2025

Robin and Varun together can paint a hall in 6 days. Robin alone can paint it in 42 days. In how many days can Varun alone paint it?

A
7
B
9
C
10
D
8
Result Summary
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NTPC Graduate Tier 1
2025 • 05 Jun, 2025 • Shift-3
Robin and Varun together can paint a hall in 6 days. Robin alone can paint it in 42 days. In how many days can Varun alone paint it?
Correct Answer
7
[Efficiency Definition]: To solve cooperative work problems, convert total days into the fraction of work completed in exactly one single day.[Combined Rate Val......
Ref/Book : NTPC Graduate Tier 1 2025
Ref. Subject Quantitative Aptitude
Chapter -
Ref. Topic Time and Work
Pg. No -
💡 Analysis & Explanation
[Efficiency Definition] ▼
To solve cooperative work problems, convert total days into the fraction of work completed in exactly one single day.
[Combined Rate Validation] ▼
If Robin and Varun together finish the task in 6 days, their combined daily efficiency is precisely 1/6 of the total work per day.
[Individual Rate Extraction] ▼
The problem states Robin alone takes 42 days, making his personal daily efficiency 1/42 of the work per day.
[Mathematical Segregation] ▼
To find Varun's exclusive daily rate, subtract Robin's rate from the combined rate: 1/6 - 1/42. Finding a common denominator (42) transforms the equation to 7/42 - 1/42 = 6/42. Simplifying this fraction yields exactly 1/7.
Conclusion ▼
Since Varun finishes 1/7 of the work daily, he requires 7 full days to complete it alone.
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