A tap can fill a tank in 4 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 from the following choices: A) 2 hr B) 2 hr 30 min C) 2 hr 50 min D) 2 hr 20 min E) 1 hr 30 min
A tap can fill a tank in 4 hours   The tap can fill half the tank in 2 hours   Remaining part = 1/2   After half the tank is filled, three more similar taps are opened.   Hence, total number of taps becomes 4.   Part filled by one tap in 1 hour = 1/4   Part filled by four taps in 1 hour = 4×1/4=1   i.e., 4 taps can fill remaining half in 30 minutes   Total time taken = 2 hour + 30 minute = 2 hour 30 minutes   Answer is 2 hr 30 min
<result>B</result>
A tap can fill a tank in 4 hours. After half the tank is filled, three more similar taps are opened. What is the total time taken to fill the tank completely?