A tap can fill a tank in 12 hours. After half the tank is filled three more similar taps are opened. What is the total time taken to fill the tank completely?
Choices.
A) 13 hrs 30 mins  B) 14 hrs 30 mins  C) 15 hrs 30 mins  D) 16 hrs 30 mins  E) 17 hrs 30 mins
Time taken by one tap to fill the tank = 6 hrs.   Part filled by the taps in 1 hour = 4 * 1/12 = 1/3   Remaining part = 1 - 1/2 = 1/2   1/3 : 1/2 :: 1 : x   x = 1/2 * 1 * 3= 
<gadget id="calculator">1/2 * 1 * 3</gadget>
<output>3/2 = around 1.5</output>
1.5 hrs= 1 hrs 30 min   So, total time taken = 13 hrs 30 mins   13 hrs 30 minsNSWER: 13 hrs 30 mins
<result>A</result>
A tap can fill a tank in 12 hours. After half the tank is filled three more similar taps are opened. What is the total time taken to fill the tank completely?