Archives

Categories

Can You Solve Dave Carpenter’s Ants On A Cube Puzzle?

I received this puzzle by email from Dave Carpenter. Eight ants start at different corners of a cube. Suddenly each ant moves to an adjacent corner at random. That is, each ant walks along one of its three adjacent edges with equal chance. What is the probability that none of the ants collide? For me … Continue reading Can You Solve Dave Carpenter’s Ants On A Cube Puzzle? Read more ›

Can You Solve This Cambridge Exam Question? Math Problem, 1802

Cambridge University asked this problem in 1802 to students seeking a bachelor’s degree. Find the sum of the following series. 1/(1×2) + 1/(2×3) + 1/(3×4) + … What is the answer? Watch the video for the solution. Can You Solve This Cambridge Exam Question? Math Problem, 1802 (Please click on that video link. YouTube has … Continue reading Can You Solve This Cambridge Exam Question? Math Problem, 1802 Read more ›

I Will Read Your Mind – Math Magic Trick Three Digit Number

Today I’ll cover a fun magic trick. Here’s a video for it. The instructions are also in text below. I Will Read Your Mind – Math Magic Trick Pick a 3 digit number with 3 different digits. Now reverse the digits to get a new number. You now have two numbers. Subtract the smaller number … Continue reading I Will Read Your Mind – Math Magic Trick Three Digit Number Read more ›

Can You Solve The Square Inside of 4 Circles Problem?

Four circles of equal size are inscribed in a square as shown in the diagram. Inside of the four circles is a smaller square tangent to each of the four circles. If the large square has a side length equal to 4, what is the area of the small square? Watch the video for a … Continue reading Can You Solve The Square Inside of 4 Circles Problem? Read more ›

Can You Find All Five Mistakes? A Fun Test Of Intelligence

Here is a fun little test of your intelligence. See if you can identify all of the problems in the following sentence. There are are five things wrong with this sentence; only geniuses will be able to to spot all of the mitstakes I explain the answer in a video. Can You Find ALL Of … Continue reading Can You Find All Five Mistakes? A Fun Test Of Intelligence Read more ›

Programmer Interview Question – The Probability Of Adjacent Seating

5 people (a, b, c, d, e) are seated randomly around a circular table. What is the probability a and b will be seated next to each other? What is the probability, if they are seated randomly in a row? What is the probability if there are n people seated randomly? Solve for random seating … Continue reading Programmer Interview Question – The Probability Of Adjacent Seating Read more ›

“Prove” 13 = 12 With Geometry. The Vanishing Line Paradox

In this post I’ll teach you a trick that fools most people. On a rectangular strip of paper, draw 13 straight lines as illustrated below. Now carefully cut the shape along the following diagonal line, from the top of the first line to the bottom of the last line. Take slide the upper piece along … Continue reading “Prove” 13 = 12 With Geometry. The Vanishing Line Paradox Read more ›

Can You Solve A Math Word Problem That Stumps US College Students? A Working Together Problem

Alice and Bob can complete a job in 2 hours. Alice and Charlie can complete the same job in 3 hours. Bob and Charlie can complete the same job in 4 hours. How long will the job take if Alice, Bob, and Charlie work together? Assume each person works at a constant rate, whether working … Continue reading Can You Solve A Math Word Problem That Stumps US College Students? A Working Together Problem Read more ›

“Prove” 0 = 1 Using Calculus Integration By Parts

Here’s a little test of your calculus skills. The integration by parts formula states: Let’s do the integral of 1/x with the following substitutions. We use the integration by parts formula. Now we simplify the right hand side and cancel like terms. And voila, we have proved 0 = 1. This is obviously an absurd … Continue reading “Prove” 0 = 1 Using Calculus Integration By Parts Read more ›