Q104
ArithmeticTime & Work, Pipes & Cisterns
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.4 hours 15 minutes
- c.3 hours 15 minutes
- d.3 hours 45 minutes
Answer: (D) 3 hours 45 minutes
One tap fills the first half in 3 hours. Four taps together fill $\frac{4}{6}$ of the tank per hour, so the second half takes $\frac{1}{2} \div \frac{2}{3} = \frac{3}{4}$ hour = 45 minutes. Total = 3 hours 45 minutes.