Joe can shovel the snow off a driveway in 4 hours. John can shovel the snow off in 7 hours. How long would it take Joe and John, working together, to shovel the snow off the driveway?

Question

anonymous · Answer

Use the Principle of Work Shared to answer this question.  T/a +T/b =1 where a=time for one individual or object to complete a job, b=time for the second individual or object to complete the job, and T=time to complete the job if they are working together.  You know each of their times, so just substitute those values into the equation and solve for T.