Pipe A is an inlet pipe that can fill an empty cistern in 69 hours. Pipe B can drain the filled cistern in 46hours. When the cistern was filled the two pipes are opened one at a time for an hour each, starting withPipe B. how long will it take for the cistern to be empty?

• 11 days 10 hours
• 11 days 7 hours
• 11 days 12 hours
• 1 days 13 hours