Question

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?

• A. 4 hours
• B. 5 hours
• C. 3 hours 30 minutes
• D. 3 hours 45 minutes

Answer 1

Answer: (D)

3 hours 45 minutes

Answer 2

The first tap fills half the tank in 3 hours. After that, four taps are opened, so the remaining half is filled at four times the rate: Time to fill the remaining half = $\frac{3}{4} = 0.75$ hours. Total time = 3 + 0.75 = 3.75 hours = 3 hours 45 minutes.