# Can You Solve This 6th Grade Geometry Problem From China?

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## Description

What is the total area of the red spots? The diagram involves a rectangle with dimensions of 10 and 20. Inside the rectangle one of its diagonals is connected. There are two circles of equal size that are tangent to each other and the rectangle. The video presents the solution to one version of the problem and then the solution to a second, much harder version, that was said to be assigned to 6th graders in China.

I read about this problem from Jin Yang on Twitter: https://twitter.com/jzy/status/759079328965505025

**Update 12 Aug: Many people suspected the second problem was too hard for 6th graders. It appears the first problem was assigned to 6th graders, and second problem (with the missing spot) was a misprint that went viral on social media. Jin Yang tweeted me with a link to the original problem assigned (in Chinese): http://wenku.baidu.com/view/de4510b0770bf78a652954a9.html

The Twitter thread from Jin Yang with the link to the original problem: https://twitter.com/jzy/status/763406201468047360

Blog post: http://wp.me/p6aMk-4Ls

There are other solution methods described on Quora: https://www.quora.com/What-is-the-area-of-the-shaded-part

If you like my videos, you can support me at Patreon: http://www.patreon.com/mindyourdecisions

Connect on social media. I update each site when I have a new video or blog post, so you can follow me on whichever method is most convenient for you.

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My Books

"The Joy of Game Theory" shows how you can use math to out-think your competition. (rated 4/5 stars on 23 reviews) http://amzn.to/1uQvA20

"The Irrationality Illusion: How To Make Smart Decisions And Overcome Bias" is a handbook that explains the many ways we are biased about decision-making and offers techniques to make smart decisions. http://amzn.to/1o3FaAg

"Math Puzzles Volume 1" features classic brain teasers and riddles with complete solutions for problems in counting, geometry, probability, and game theory. Volume 1 is rated 4.5/5 stars on 11 reviews. http://amzn.to/1GhUUSH

"Math Puzzles Volume 2" is a sequel book with more great problems. http://amzn.to/1NKbyCs

"Math Puzzles Volume 3" is the third in the series. http://amzn.to/1NKbGlp

"40 Paradoxes in Logic, Probability, and Game Theory" contains thought-provoking and counter-intuitive results. (rated 4.9/5 stars on 7 reviews) http://amzn.to/1LOCI4U

"The Best Mental Math Tricks" teaches how you can look like a math genius by solving problems in your head (rated 4.7/5 stars on 3 reviews) http://amzn.to/18maAdo

"Multiply Numbers By Drawing Lines" This book is a reference guide for my video that has over 1 million views on a geometric method to multiply numbers. http://amzn.to/XRm7M4

I read about this problem from Jin Yang on Twitter: https://twitter.com/jzy/status/759079328965505025

**Update 12 Aug: Many people suspected the second problem was too hard for 6th graders. It appears the first problem was assigned to 6th graders, and second problem (with the missing spot) was a misprint that went viral on social media. Jin Yang tweeted me with a link to the original problem assigned (in Chinese): http://wenku.baidu.com/view/de4510b0770bf78a652954a9.html

The Twitter thread from Jin Yang with the link to the original problem: https://twitter.com/jzy/status/763406201468047360

Blog post: http://wp.me/p6aMk-4Ls

There are other solution methods described on Quora: https://www.quora.com/What-is-the-area-of-the-shaded-part

If you like my videos, you can support me at Patreon: http://www.patreon.com/mindyourdecisions

Connect on social media. I update each site when I have a new video or blog post, so you can follow me on whichever method is most convenient for you.

My Blog: http://mindyourdecisions.com/blog/

Twitter: http://twitter.com/preshtalwalkar

Facebook: https://www.facebook.com/pages/Mind-Your-Decisions/168446714965

Google+: https://plus.google.com/108336608566588374147/posts

Pinterest: https://www.pinterest.com/preshtalwalkar/

Tumblr: http://preshtalwalkar.tumblr.com/

Instagram: https://instagram.com/preshtalwalkar/

Patreon: http://www.patreon.com/mindyourdecisions

Newsletter (sent about 2 times a year): http://eepurl.com/KvS0r

My Books

"The Joy of Game Theory" shows how you can use math to out-think your competition. (rated 4/5 stars on 23 reviews) http://amzn.to/1uQvA20

"The Irrationality Illusion: How To Make Smart Decisions And Overcome Bias" is a handbook that explains the many ways we are biased about decision-making and offers techniques to make smart decisions. http://amzn.to/1o3FaAg

"Math Puzzles Volume 1" features classic brain teasers and riddles with complete solutions for problems in counting, geometry, probability, and game theory. Volume 1 is rated 4.5/5 stars on 11 reviews. http://amzn.to/1GhUUSH

"Math Puzzles Volume 2" is a sequel book with more great problems. http://amzn.to/1NKbyCs

"Math Puzzles Volume 3" is the third in the series. http://amzn.to/1NKbGlp

"40 Paradoxes in Logic, Probability, and Game Theory" contains thought-provoking and counter-intuitive results. (rated 4.9/5 stars on 7 reviews) http://amzn.to/1LOCI4U

"The Best Mental Math Tricks" teaches how you can look like a math genius by solving problems in your head (rated 4.7/5 stars on 3 reviews) http://amzn.to/18maAdo

"Multiply Numbers By Drawing Lines" This book is a reference guide for my video that has over 1 million views on a geometric method to multiply numbers. http://amzn.to/XRm7M4

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