A tap can fill a tank in 6 hours. After half the tank is filled then 3 more similar taps are opened. What will be total time taken to fill the tank completely.  Choose the most appropriate option:
A) 2 hours 30 mins B) 2 hours 45 mins C) 3 hours 30 mins D) 3 hours 45 mins E) None of these
Explanation:   Half tank will be filled in 3 hours   Lets calculate remaining half,   Part filled by the four taps in 1 hour = 4*(1/6) = 2/3   Remaining part after 1/2 filled = 1-1/2 = 1/2   2/3:1/2::1:X   =&gt;X=(1/2∗1∗32)   =&gt;X=3/4hrs=45 mins   Total time = 3 hours + 45 mins = 3 hours 45 mins   Option 3 hours 45 mins
<result>D</result>
A tap can fill a tank in 6 hours. After half the tank is filled then 3 more similar taps are opened. What will be total time taken to fill the tank completely.