How fast can they do a job

Question

Ken can paint in 12 hours, Dwayne can paint in 16 hours how fast can they paint together?

Answer 1

You might want to look at it this way.

rates 1/16 and 1/12. Therefore for time t

1/16 t + 1/12 t = 1 job done. Multiply by 48 and you should get the same answer, a little different approach.

Answer 2

Ken can do 1/12 of the job in an hour

Dwayne can do 1/16 of the job in an hour

Together they can do 1/12 + 1/16 = 4/48 + 3/48 = 7/48 of the job in an hour.

So to do the whole job would take 48/7 hours = 6.857 hours