Question

Choose the correct answer from the alternatives given :
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. 3 hours 15 min.
• B. 3 hours 45 min.
• C. 4 hours.
• D. 4 hours 15 min.

Answer 1

The correct option is B 3 hours 45 min.

Let the capacity of tank be $6$ units.
Tank filled by A per hour = $\frac{6}{6}=1$ unit hr.

Required time for filling half the tank = $\frac{3}{1}$ $=3$ hours
Remaining volume left $=6-3=3$ units

Now according to the questions, $\therefore$ Required time = $\frac{3}{(1+3)}=\frac{3}{4}\times 60=45min.$

Total time = $3$ hrs + $45$ min = $3$ hrs $45$ min.