Multiple choice

An inlet pipe A can completely fill a water tank of 25000 litres capacity in 10 hours but an outlet pipe B can empty the completely filled tank in 40 hours. Q I: In how many hours pipe A and Pipe B together will fill half of the tank? Q II: In how many hours pipe A alone fill 70% of the capacity of the tank?

  1. Q I > Q II

  2. Q I ≥ Q II

  3. Q I < Q II

  4. Q I ≤ Q II

  5. Q I = Q II or cannot be determined

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Pipe A fills at 2500 L/hr (25000÷10), Pipe B empties at 625 L/hr (25000÷40). Combined rate: 1875 L/hr. Q I: Half tank = 12500 L, time = 12500÷1875 = 6.67 hours. Q II: 70% of 25000 = 17500 L, time = 17500÷2500 = 7 hours. Since 6.67 < 7, Q I takes less time than Q II, making Q I < Q II correct.