Two pipes P and Q can fill a cistern in 12 and 14 minutes respectively. Both are opened together, but at the end of 3 minutes the first is turned off. How much longer will the cistern take to fill?  Choose the correct choice from the following answers.
A) 11 1/2 min
B) 11 1/4 min
C) 11 2/4 min
D) 11 1/5 min
E) 10 1/2 min
3/12 + x/14 = 1   x= 10 1/2   Answer: 10 1/2 min
<result>E</result>
Two pipes P and Q can fill a cistern in 12 and 14 minutes respectively. Both are opened together, but at the end of 3 minutes the first is turned off. How much longer will the cistern take to fill?