Data Sufficiency questions can be challenging to get your mind around on the GMAT under the best of circumstances, and they’re made even harder when they combine a number of different elements and nuances that make determining sufficiency even more difficult.

Question #424 from the GMAT Official Guide 2020 is one of those questions that the test makers deem to be “Difficult” and that I get a lot of questions about from my students. Here’s a video I created that explains the best approach to this particular problem. I think it will help you better understand ratios so that you can solve similar questions quickly and accurately in the future. Enjoy!

If you found this video helpful, I’ve recorded detailed answer explanations for every other question in the GMAT Official Guide 2020 and included them with certain of our GMAT prep course packages. Register for one today and take your GMAT prep to the next level!