Question

Joseph and Chandra are cleaning their house which has 12 rooms, each about the same size. If Joseph cleans them by himself, it takes him 6 hours. If Chandra cleans them by herself, it takes her 12 hours. If they both clean the house, they will finish in 4 hours. If they work together, how many rooms will Chandra clean and how many will Joseph clean?

Answer 1

9 hours
the average between them is 9
12+6=18
18/2=9

Answer 2

It should be 6 and 6, with 12 rooms, however Joseph is speedier than Chandra, I believe that he will clean more than half the rooms, 8 or 9.