Bob and Alice can finish a job together in 3 hours.

Hi All,

This prompt is a variation on a Work Formula question. It can actually be solved in a variety of ways - based on the information that we're given, here's a method that minimizes the number of calculations that you have to do:

We're told that Bob and Alice can finish a job together in 3 hours and that Bob can do the job by himself in 5 hours. We're asked what PERCENT of the job that Alice completes.

Since Bob can do the job in 5 hours, he completes 1/5 of the job per hour. We're told that he and Alice BOTH work for 3 hours, so Bob completes...

(3 hours)(1/5 of the job per hour) = 3/5 of the job = 60% of the job.

Since Bob completes 60% of the job, Alice must complete the other 40%.

Final Answer:

GMAT assassins aren't born, they're made,
Rich