Everyone Got This SAT Math Question Wrong
- 6 years ago
Problem: Circle A has 1/3 the radius of circle B, and circle A rolls one trip around circle B. How many times will circle A revolve in total?\r
\r
1982 SAT Question\r
In the figure above, the radius of circle A is one third the radius of circle B. Starting from position shown in figure, circle A rolls around circle B. At the end of how many revolutions of circle A will the center of circle A first reach its starting point?\r
\r
(a) 3/2 \r
(b) 3 \r
(c) 6 \r
(d) 9/2 \r
(e) 9\r
\r
Blog post summary: \r
\r
Sources:\r
\r
\r
\r
Also see the Coin Rotation Paradox\r
\r
\r
Update: some people have made really cool interive worksheets at Geogebra. You should check these out!\r
\r
Rolling Circles: \r
Rolling coin paradox: \r
A question about a rolling circle: \r
\r
If you like my videos, you can support me at Patreon:\r
\r
\r
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.\r
\r
My Blog: \r
Twitter: \r
Facebook: \r
Google+: \r
Pinterest: \r
Tumblr: \r
Instagram: \r
Patreon: \r
\r
Newsletter (sent only for big news, like a new book release): \r
\r
If you buy from the links below I may receive a commission for sales. This has no effect on the price for you.\r
\r
My Books\r
The Joy of Game Theory shows how you can use math to out-think your competition. (rated 3.8/5 stars on 31 reviews)\r
\r
\r
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. (rated 4.6/5 stars on 3 reviews)\r
\r
\r
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 4.4/5 stars on 13 reviews. \r
\r
\r
Math Puzzles Volume 2 is a sequel book with more great problems. (rated 4.3/5 stars on 4 reviews)\r
\r
\r
Math Puzzles Volume 3 is the third in the . (rated 3.8/5 stars on 5 reviews)\r
\r
\r
40 Paradoxes in Logic, Probability, and Game Theory contains thought-provoking and counter-intuitive results. (rated 4.3/5 stars on 12 reviews)\r
\r
\r
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 4 reviews) \r
\r
\r
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. (rated 5/5 stars on 3 reviews)\r
\r
1982 SAT Question\r
In the figure above, the radius of circle A is one third the radius of circle B. Starting from position shown in figure, circle A rolls around circle B. At the end of how many revolutions of circle A will the center of circle A first reach its starting point?\r
\r
(a) 3/2 \r
(b) 3 \r
(c) 6 \r
(d) 9/2 \r
(e) 9\r
\r
Blog post summary: \r
\r
Sources:\r
\r
\r
\r
Also see the Coin Rotation Paradox\r
\r
\r
Update: some people have made really cool interive worksheets at Geogebra. You should check these out!\r
\r
Rolling Circles: \r
Rolling coin paradox: \r
A question about a rolling circle: \r
\r
If you like my videos, you can support me at Patreon:\r
\r
\r
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.\r
\r
My Blog: \r
Twitter: \r
Facebook: \r
Google+: \r
Pinterest: \r
Tumblr: \r
Instagram: \r
Patreon: \r
\r
Newsletter (sent only for big news, like a new book release): \r
\r
If you buy from the links below I may receive a commission for sales. This has no effect on the price for you.\r
\r
My Books\r
The Joy of Game Theory shows how you can use math to out-think your competition. (rated 3.8/5 stars on 31 reviews)\r
\r
\r
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. (rated 4.6/5 stars on 3 reviews)\r
\r
\r
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 4.4/5 stars on 13 reviews. \r
\r
\r
Math Puzzles Volume 2 is a sequel book with more great problems. (rated 4.3/5 stars on 4 reviews)\r
\r
\r
Math Puzzles Volume 3 is the third in the . (rated 3.8/5 stars on 5 reviews)\r
\r
\r
40 Paradoxes in Logic, Probability, and Game Theory contains thought-provoking and counter-intuitive results. (rated 4.3/5 stars on 12 reviews)\r
\r
\r
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 4 reviews) \r
\r
\r
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. (rated 5/5 stars on 3 reviews)\r