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?
Choose the correct choice: A) 3 hrs 25 min B) 3 hrs 45 min C) 3 hrs 48 min D) 3 hrs 35 min E) 2 hrs 45 min
Explanation:   Time taken by one tap to fill half of the tank = 3 hrs.   Part filled by the four taps in 1 hour ={\color{Black} \left ( 4\times \frac{1}{6} \right )=\frac{2}{3}}   Remaining part ={\color{Black} \left ( 1- \frac{1}{2} \right )=\frac{1}{2}}   {\color{Black} \therefore \frac{2}{3}:\frac{1}{2} ::1:x}   {\color{Black} \Rightarrow x=\left ( \frac{1}{2} \times 1\times \frac{3}{2}\right )=\frac{3}{4}}   So, total time taken = 3 hrs. 45 mins.   Answer: 3 hrs 45 min) 3 hrs 45 min
<result>B</result>
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?