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.