Two pipes P and Q can fill a cistern in 12 and 15 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?	Options
A) 11 1/8  B) 11 1/4  C) 11 1/1  D) 11 1/2  E) 11 1/9
Explanation:   3/12 + x/15 = 1   x= 11 1/4   Answer:11 1/4
<result>B</result>
Two pipes P and Q can fill a cistern in 12 and 15 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?