2020-2024 Form

Instructions and help about Please Circle One N P P A M D D O

the problem in this video comes from a 1982 sat exam this math problem was so hard that no one selected the correct answer can you figure it out in the following figure circle a has one third the radius of circle b circle a rolls around circle b one trip back to its starting point how many times will circle a revolve in total the answer choices are three halves three six nine halves and nine get out some pencil and paper and see if you can figure it out remember this was on the sat so it's a timed exam and the students would have had to figure it out just using pencil and paper here is what the test preparers thought when they made the question if circle a rolls around a distance of three times its circumference if you do it very carefully you'll find that circle a will roll around three times in total and that's what they thought the correct answer should be but let's do a little experiment and see what actually happens if we have circle a rolling around circle b i've made cardboard c