Solved UPSC CDS/OTA Question
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Q · Time and WorkMedium · 45s
An inlet fills a tank in 5 hours. An outlet can empty it in 8 hours. If both are opened together for 2 hours, then the outlet is closed, how much longer will it take to fill the tank?
TopicTime and Work
Question Typemultiple choice
DifficultyMedium
Marking+1 / −0.25
Test Duration30 min
Step-by-Step Solution
The complete worked solution.
Every step explained — no skipped algebra.
Net rate = 1/5 - 1/8 = 3/40. In 2 hours: 3/20 filled. Remaining = 17/20, filled by inlet at 1/5/hr → 17/4 = 4.25 hours.
Final Answer: Option C — 3 hours