Tap 'A' can fill the tank completely in 6 hrs while tap 'B' can empty it by 12 hrs. By mistake, the person forgot to close the tap 'B', As a result, both the taps, remained open. After 7 hrs, the person realized the mistake and immediately closed the tap 'B'. In how much time now onwards, would the tank be full?  Choose the correct choice from the following answers
A) 2.5 hours	B) 4.5 hours	C) 5.5 hours	D) 1.5 hour	E) None of these
Explanation :   Tap A can fill the tank completely in 6 hours   =&gt; In 1 hour, Tap A can fill 1⁄6 of the tank   Tap B can empty the tank completely in 12 hours   =&gt; In 1 hour, Tap B can empty 1⁄12 of the tank   i.e., In one hour, Tank A and B together can effectively fill 1⁄6 - 1⁄12 = 1⁄12 of the tank   =&gt; In 7 hours, Tank A and B can effectively fill 1⁄12 × 7 = 7/12 of the tank.   Time taken to fill the remaining 1−(7/12) = 5/12 of the tank = (5/12)/(1/6)= 
<gadget id="calculator">(5/12)/(1/6)</gadget>
<output>5/2 = around 2.5</output>
2.5 hours. 2.5 hoursnswer : Option 2.5 hours
<result>A</result>
Tap 'A' can fill the tank completely in 6 hrs while tap 'B' can empty it by 12 hrs. By mistake, the person forgot to close the tap 'B', As a result, both the taps, remained open. After 7 hrs, the person realized the mistake and immediately closed the tap 'B'. In how much time now onwards, would the tank be full?