Two pipes A and B together can fill a cistern in 4 hours. Had they been opened separately, then B would have taken 6 hours more than A to fill the cistern. How much time will be taken by A to fill the cistern separately?
Choose the correct choice from the following:
A) 1 hour
B) 2 hours
C) 6 hours
D) 8 hours
E) 9 hours
If A takes x hrs, then B takes x+6 hrs   1/x + 1/ (x+6) = 1/4   solving it, we get   x= 6 hours   ANSWER:6 hours
<result>C</result>
Two pipes A and B together can fill a cistern in 4 hours. Had they been opened separately, then B would have taken 6 hours more than A to fill the cistern. How much time will be taken by A to fill the cistern separately?