Pipe A can fill a tank in 2 hours. Due to a leak at the bottom, it takes 4 hours for the pipe A to fill the tank. In what time can the leak alone empty the full tank?	Choose the correct choice from the following answers:
A) 2
B) 5
C) 6
D) 4
E) 1
Let the leak can empty the full tank in x hours 1/2 - 1/x = 1/4   =&gt; 1/x = 1/2 - 1/4 = 1/4   =&gt; x = 4. Answer:4
<result>D</result>
Pipe A can fill a tank in 2 hours. Due to a leak at the bottom, it takes 4 hours for the pipe A to fill the tank. In what time can the leak alone empty the full tank?