If a young son works quickly for 2 hours and prepares 16 items in a day, and his old father works slowly for 8 hours and prepares 24 items in a day, which of the following is true?
A, B and C can complete a task together in 10 days. A and B would need 12 days if only the two of them worked, while B and C would take 20 days if only the two of them worked. If B worked alone, how many days would she take to complete the task?
Pipes A and C can fill an empty cistern in 32 and 48 hrs, respectively while Pipe B can drain the filled cistern in 24hrs. If the three pipes are turned on together when the cistern is empty, how many hrs will it take for the cistern to be 2/3 full?