Question

Adam and Kevin are roommates. Adam can clean their apartment in 45 minutes. Kevin can clean it in 60 minutes. Rounded to the nearest minute, how much time will it take if they work together?

Answer 1

Rate of Adam = 45 min : 1 apartment
Rate of Kevin = 60 min : 1 apartment
If Adam works for 15 min he can cover: 1/3 apartment
If Kevin works for 15 min he can cover : 1/4 apartment
In 30 min Adam and Kev cover 1/3 + 1/4 = 7/12
For 12/12, whole apartment = (30/7) x 12
= 4.2857 x 12
51.428
= 51 minutes