Two pipes A and B can fill a cistern in 12 and 15 minutes respectively. Both are opened together but after 3 minutes A is turned off. After how much more time will the cistern be filled? Answers.
A) 8 1/8 B) 8 1/9 C) 8 1/4 D) 8 1/1 E) 8 1/5
3/12 + (3 + x)/15 = 1   x = 8 1/4   Answer:8 1/4
<result>C</result>
Two pipes A and B can fill a cistern in 12 and 15 minutes respectively. Both are opened together but after 3 minutes A is turned off. After how much more time will the cistern be filled?