Question

You can do one-half of a job in an hour. Your friend can do one-third of the same job in an hour. How long will it take to do the job if you work together? Write your answer as a decimal.

Answer 1

You do:  1/2  job/hr

Your friend does:  1/3  job/hr

Together:       (1/2 + 1/3)  job / hr

                   = (3/6 + 2/6)  job/hr

                   =    5/6          job/hr .

Since you do  5/6 job/hr, the corresponding
inverse unit rate is 
                                 6/5  hr/job

                              = 1 and 1/5 hr/job

                              =  1.2 hours/job

                              = 1 hour 12 minutes  per job.