A tap can fill a tank in 6 hours. After half the tank is filled, three more similar taps are opened. What is the total time taken to fill the tank completely?

3 hours 45 minutes

The correct answer is Option (4) → 3 hours 45 minutes

A tap can fill a tank in = 6 hours

Let the total capacity of the tank = 6 liters.

So the efficiency of the tap will be = \(\frac{6}{6}\) = 1 liter/hour

After half the tank filled means,

3 liters water has been filled in 3 hours, now 3 more taps of similar efficiencies are opened then the total efficiency will be = 1 + 1 + 1 + 1 = 4 Liters/min

Remaining amount of water = 6 - 3 = 3 liters.

Time taken = \(\frac{3}{4}\) × 60 = 45 minutes

Total time taken = 3 hours and 45 minutes.