Question
Two pipes A and B can fill a cistern in 12 minutes and 15 minutes respectively while a third pipe C can empty the full tank in 6 minutes . A and B are kept open for 5 minutes in the beginning and then C is also opened . In what time is the cistern emptied ?
Answer: Option D
Was this answer helpful ?
Part filled in 5 min. = `5(1/12 + 1/15) = (5 xx 9/60) = 33/4`
part emptied in 1 min. . when all the pipes are opened
= `1/6 - (1/12 + 1/15) = (1/6 - 3/20) = 1/60`
Now , `1/60` part is emptied in 1 min.
`:.` `3/4` part will be emptied in `(60 xx 3/4)` = 45 min.
Was this answer helpful ?
More Questions on This Topic :
Latest Videos
Latest Test Papers
Submit Solution