**UPDATE: We replaced the old GMAT Tuesday in this post with a new video because one of our readers spotted an error and brought it up to us–thank you, Rose!**

Hello! 🙂

Today, it’s fraction time! I am answering a question that one of your fellow GMAT-studiers asked about comparing fractions. Watch the video to learn more on this topic, and check out Mike McGarry’s blog post for even more tips!

If you have any questions about this, be sure to leave them in the comments below.

And as usual, here’s a still of this week’s board work:

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Hi Kevin!

Very nice tip to compare fractions!

My question is, which would be a fast way to do this comparison when you have, let’s say, 5 fractions to compare. In that case I would have to cross multiply 10 times and that’s too time consuming!

Do you know where can I find a trick to solve this kind of PS question?

Thanks!

Hi Fecob!

Happy to help! If you have 5 fractions to work with, then you’ll want to find other ways to eliminate some of your options. Usually, you will have enough information in the question to narrow in on two or three fractions. You should never have to compare all 5 fractions to each other to solve a problem. I recommend looking at the information provide to see how you can eliminate wrong answers and avoid doing all these calculations. As you said, doing 10 calculations on the test is way too time consuming. 😀

If you have a specific question from the official materials that involves comparing 5 fractions, please pass it along and I’ll try to show you how to approach the question. 😀

I hope that this is helpful. 😀

Cheers,

Kevin

Hi Kevin,

Your tip is rite regarding cross multiply the fractions. But I think you did it wrong in the video.

LHS = 3×43 i.e. 129

RHS = 7×19 i.e. 133

Therefore the RHS > LHS i.e. 3/19 < 7/43

Please check!

Hi Rose,

You are 100% correct! I made a mistake here! I will re-record the video soon to correct the error! Thank you for noticing and checking my work. 😀

I always check your videos Kevin. 😀

But I feel the videos should be bit longer to cover a broader spectrum.

Most of the time the topics that are covered often leaves me curious and unsatisfied. I’m sure others would agree.

Just letting you guys know 🙂

Hi Rose, thanks for the feedback! We love hearing this type of comment from students! 😀

We are aiming to keep the videos under 10 minutes because we find that students learn best with smaller chunks of information. Anything over 10 minutes runs the risk of making students bored or lose focus. Actually, I feel like I have succeed in some way if you leave the video curious. Cultivating curiosity is the most important aspect of learning. I can’t help every student with every issue, but if I can make students curious, then I have sent them on the path to discovery and learning. 😀

With that said, we could definitely have more videos that build on top of each other so that students could click to the next video for further information about the topic. If you have any suggestions for topics or more in depth videos, please let us know.

And as always, if you do have questions or you watch a video and you are still confused, leave a comment and I will do my best to help.

Great tip- To clarify my understanding: The fraction whose denominator when cross multiplied yielded a larger number is considered bigger of the two. Is that correct?

Happy to help, SJ! 🙂 If you have your fractions lined up next to each other, one on the left and one on the right, cross multiply. Whichever number is bigger, that’s the side with the bigger fraction.