Multiple choice

(\text{Inlet Pipe A can fill the tank in one hour. Outlet pipe B can empty it in 3 hours. Both pipes working together may fill the tank at a rate of 8000 lit/hour. Find the capacity of the tank.})

  1. $12000 lit$
  2. $8000 lit$
  3. $6000 lit$
  4. $4000 lit$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Inlet A fills 1 tank/hour (rate +1 tank/hr), outlet B empties in 3 hours (rate -1/3 tank/hr). Combined rate = 1 - 1/3 = 2/3 tank/hr. If 2/3 tank = 8000 lit/hr, then full tank = 8000 ÷ (2/3) = 8000 × (3/2) = 12000 lit. Option B (8000 lit) is just the fill rate, not capacity. Option C (6000 lit) would mean combined rate is 4/3 tank/hr, impossible. Option D (4000 lit) gives combined rate 2 tank/hr, exceeding inlet's capacity.

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