Question

There are five containers A, B, C, D and E each containing 1200 litres of water. The water is being pumped from one tank to another as follows:
From A to B at 30 litres/minute
From C to A at 60 litres/minute
From A to E at 20 litres/minute
From C to D at 50 litres/minute
From D to B at 80 litres/minute
From B to C at 60 litres/minute
From E to D at 10 litres/minute
From E to A at 10 litres/minute
Which tank gets emptied first?

• A. A
• B. B
• C. C
• D. D
• E. E

Answer 1

The Correct Option is C

The correct answer is option (C):

C

Let's analyze the water flow in each tank to determine which one empties first. We need to track the inflow and outflow for each tank. Since the tanks start with 1200 liters of water each, the tank with the highest net outflow (water leaving the tank faster than it enters) will empty the fastest.

Tank A:
* Inflow: From C (60 L/min) and E (10 L/min) - total 70 L/min
* Outflow: To B (30 L/min) and E (20 L/min) - total 50 L/min
* Net change: +20 L/min (70 L/min in - 50 L/min out). This tank is gaining water.

Tank B:
* Inflow: From A (30 L/min) and D (80 L/min) - total 110 L/min
* Outflow: To C (60 L/min) - total 60 L/min
* Net change: +50 L/min (110 L/min in - 60 L/min out). This tank is gaining water.

Tank C:
* Inflow: From B (60 L/min) - total 60 L/min
* Outflow: To A (60 L/min) and D (50 L/min) - total 110 L/min
* Net change: -50 L/min (60 L/min in - 110 L/min out). This tank is losing water at a rate of 50 L/min.

Tank D:
* Inflow: From C (50 L/min) and E (10 L/min) - total 60 L/min
* Outflow: To B (80 L/min) - total 80 L/min
* Net change: -20 L/min (60 L/min in - 80 L/min out). This tank is losing water.

Tank E:
* Inflow: From A (20 L/min) - total 20 L/min
* Outflow: To D (10 L/min) and A (10 L/min) - total 20 L/min
* Net change: 0 L/min. This tank's water level remains constant.

Tank C has the largest net outflow of 50 L/min. Since it's losing water at the fastest rate, it will be the first tank to empty. Therefore, the correct answer is C.