A tap can fill a tank in 10 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 options:
A) 5hr 45min	B) 6hr 30min	C) 4hr	D) 3hr 25min	E) 2hr 10min
Time taken by one tap to fill the half tank = 5 hr   part filled by the 4 taps in 1hour = 4*1/6 = 2/3   Remaining part = 1-1/2 = 1/2   2/3:1/2::1:x   x = 3/4hr = 45min   Total time taken = 5hr 45min   5hr 45minnswer is 5hr 45min
<result>A</result>
A tap can fill a tank in 10 hours. After half the tank is filled, three more similar taps are opened. What is the total time taken to fill the tank completely?