Free GRE Prep Hour: Combinatorics on the GRE

[@anishjoshi1999]

very helpful! but the last problem was wrong with the first option, so the answer will be 540, and the second one is 1350, so the total combination is (540 + 1350 = 1890).

[@manhattanprepgre7390]

Hi, Anish! I'm glad that the lesson was beneficial to you! And, great catch. You are correct that the final answer should be 1890 - in the options, I canceled the 4s, when they should have reduced to 2. The actual number for 1 protein should be 540, the actual number for 2 proteins should be 1350. Apologies for the error!

[@michaelwalker327]

@@manhattanprepgre7390 Thanks for replying to this, I also got 1890 and was quite confident until I saw your answer. Great series so far.

[@User-q1v5u]

❤❤❤

[@rohitbhatt1815]

yeah u are correct for a minute i was confused how he got 270 and 675

[@ShahroozSaeed-h7t]

YOU ABSOLUTE GOAT, I use to struggle with these questions. Now i answer them correctly in half the time

[@lordribs]

Glad to be here

[@manhattanprepgre7390]

Hi, YJR. We're glad to have you here! :)

[@urozaliyevnavruzbek627]

Thank you helpful gre lessons! But Last problem was not right. Of course ,You are the best teacher this section.Good luck!

[@manhattanprepgre7390]

Hi, Urozaliyev! Thanks for that - both the compliment, and the great catch on the final question! We're so glad that you enjoyed the video. And, you are - the answer for that final question should actually be 1890 - in the options, I canceled the 4s, when they should have reduced to 2. The actual number for 1 protein should be 540, the actual number for 2 proteins should be 1350. Apologies for the error!

[@reynardonainggolan1298]

Awesome. Like Cat Powell

[@koshkindmitry]

There is a mistake at 1:00:09. The teacher cancels 4 with 2x1 without retaining 2 in the numerator. Same mistake at 1:03:29. @anishjoshi1999 is right, 1890

[@manhattanprepgre7390]

Hey, Dmitry! Good catch! You're totally right, I made the same mistake again *facepalm.* Sorry about that! It should only cancel to 2, making the end result 540, not 270. And, the final question should have been 1890 - in the options, I canceled the 4s, when they should have reduced to 2. The actual number for 1 protein should be 540, the actual number for 2 proteins should be 1350. Apologies for those errors!

[@TheRug1998]

2! does not equal 4 but he solves it as such on the last taco problem

[@ShaqFPS]

Very helpful. But I think the math was wrong for the very last question

[@manhattanprepgre7390]

Hi, Shaq. I'm glad you found the lesson helpful! And good catch - in the options, I canceled the 4s, when they should have reduced to 2. The actual number for 1 protein should be 540, the actual number for 2 proteins should be 1350, and the final answer should be 1890. Apologies for the error!