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Category Archives: Test your intuition
False Beliefs in Mathematics
Test your intuition: For two n by n matrices A and B, is it always the case that tr(ABAB) = tr(ABBA)? Advertisements
Posted in Mathematics over the Internet, Test your intuition
Tagged Mathoverflow, Test your intuition
6 Comments
Test Your Intuition (12): Perturbing a Polytope
Let P be a ddimensional convex polytope. Can we always perturb the vertices of P moving them to points with rational coordinates without changing the combinatorial structure of P? In order words, you require that a set of vertices whose … Continue reading
Posted in Convex polytopes, Test your intuition
Tagged Convex polytopes, Test your intuition
4 Comments
Test Your Intuition (11): Is it Rational to Insure a Toaster
Here is a question from last year’s exam in the course “Basic Ideas of Mathematics”: You buy a toaster for 200 NIS ($50) and you are offered one year of insurance for 24 NIS ($6). a) Is it … Continue reading
Posted in Probability, Rationality, Teaching, Test your intuition
Tagged Insurance, Test your intuition
18 Comments
Test Your Intuition (10): How Does “Random Noise” Look
This is a bit unusual post in the “test your intuition” corner as the problem is not entirely formal. How does random noise in the digital world typically look? Suppose you have a memory of n bits, or a memory based on a larger … Continue reading
Answer to Test Your Intuition (9)
Two experimental results of 10/100 and 15/100 are not equivalent to one experiment with outcomes 3/200. (Here is a link to the original post.) One way to see it is to think about 100 experiments. The outcomes under the null … Continue reading
Buffon’s Needle and the Perimeter of Planar Sets of Constant Width
Here is an answer to “Test your intuition (8)”. (Essentially the answer posed by David Eppstein.) (From Wolfram Mathworld) Buffon’s needle problem asks to find the probability that a needle of length will land on a line, given a floor … Continue reading
Test Your Intuition (8)
Consider all planar sets A with constant width 1. Namely, in every direction, the distance between the two parallel lines that touch A from both sides is 1. We already know that there exists such sets other than the circle … Continue reading
Test Your Intuition (7)
Consider the following game: you have a box that contains one white ball and one black ball. You choose a ball at random and then return it to the box. If you chose a white ball then a white ball is added to … Continue reading
Test Your Intuition (6)
This is not as clear cut a question as the earlier ones, and if you do not know an answer then it will be difficult to figure one out just based on intuition. (But perhaps possible). If you are intrigued by … Continue reading
Test Your Intuition (5)
(Not such a set) consider a planar set A with the following property. In every direction, the distance between the two parallel lines that touch A from both sides is the same! Must A be a circle?