Two pipes P and Q can fill a cistern in 12 and 19 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) 14 1/4 min
C) 11 2/4 min
D) 11 1/5 min
E) 11 7/4 min
3/12 + x/19 = 1   x= 14 1/4   Answer: 14 1/4 min
<result>B</result>
Two pipes P and Q can fill a cistern in 12 and 19 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?