Solved UPSC CDS/OTA Question
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Q · Time and WorkMedium · 45s
Pipe A can fill a tank in 8 hours, Pipe B in 12 hours. Both are opened together for 3 hours, then Pipe B is closed. How long will it take Pipe A alone to fill the remaining 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.
In 3 hours, they fill 3×(1/8+1/12)=3×(5/24)=15/24=5/8 tank. Remaining = 3/8, Pipe A fills at 1/8 per hour → 3 hours more.
Final Answer: Option B - 3 hours