At any rate…
(This is one of a series of GMAT tips that we offer on our blog.)
Rate problems on the GMAT can take a variety of forms, and can often be time consuming for test takers. They also offer a challenge for students who rely on memorization, as it can be trickier than expected to apply the correct relationship between the rate, distance, and time variables.
For a foolproof way to remember the proper relationship, keep in mind that you will almost certainly encounter a rate on your drive to the test center: Miles per hour. Because the word “per” indicates division, you can remember that the rate is the distance (miles) divided by the time (hour). Accordingly, R = D/T.
For difficult rate problems, keep in mind that the challenge is usually created by having multiple variables. The key is that there will generally be a relationship between the distances and times of the two items. Suppose a question asks when a car will catch up to a bicycle; they can only catch up at the same time, and so there will be a relationship between the “T” variable in each rate equation. Furthermore, when they meet they will be at the same point, and there will be a relationship between the “D” variables, as well.
For more practice with rate problems, the Veritas Prep syllabus offers both a Problem Solving and Advanced Word Problems lesson.