I think that most people are familiar with Sudoku puzzles. There are some interesting questions that can be asked such as what is the minimum number of the 81 boxes in the grid that need to be filled in initially (the ‘clues’) in order to be able to obtain a unique solution?
It is known that for at least some puzzles one can obtain a unique solution with 17 clues, and no one had found any puzzles with 16 clues that had unique solutions. But is 17 the minimum number required? If you [Read more…]
I got the lightning puzzle that I posed yesterday from the latest book by Steven Pinker The Better Angels of Our Nature: Why Violence Has Declined that I reviewed in December. He uses it to illustrate that our intuitive notions of randomness and probability can easily lead us astray.
Here is the problem again.
Suppose you live in a place that has a constant chance of being struck by lightning at any time throughout the year. Suppose that the strikes are random: every day the chance of a strike is the same, and the rate works out to one strike a month. Your house is hit by lightning today, Monday. What is the most likely day for the next bolt to strike your house?
Here is his answer followed by [Read more…]
Since I have been taking about probabilities recently, here is a little puzzle for people to ponder overnight.
Suppose you live in a place that has a constant chance of being struck by lightning at any time through the year. Suppose that the strikes are random: every day the chance of a strike is the same, and the rate works out to one strike a month. Your house is hit by lightning today, Monday. What is the most likely day for the next bolt to strike your house?
Feel free to post your answers in the comments. I will give the answer tomorrow along with a discussion.
Blogs with homework. Now there’s a novel concept!
Update: The solution and discussion are posted here.
Political cartoonist Ted Rall points out that it does not mean the same thing to everyone.
When Sgt. Justin Griffith’s efforts to gain formal recognition of atheists and organize the Rock Beyond Belief event reached the ears of Fox News, they naturally didn’t like it. They interviewed him and did their usual [Read more…]
In response to my post on random drug testing in Florida, commenter Scott mentioned the danger of false positives and said that a second test in his case cleared him of having taken drugs. My advice to anyone is that whenever you take a high-stakes test for anything that has a small incidence in the general population (drugs, diseases, whatever) and it comes out positive, always consider asking for a second test.
Here’s why. [Read more…]
It is always interesting to see religious people trying to find ways to reconcile modern science with their religious texts. For people who have a literal interpretation of the Bible, the task is much harder, with the Genesis story being a nightmare. This is not because the Genesis story is particularly crazier than the other miraculous stories in the Bible but because it is the most familiar and you cannot easily finesse it away. Everyone knows the general outlines of it, even if they are [Read more…]
Aasif Mandvi from The Daily Show goes to Florida to investigate their policy of forcing people to take drug tests in order to get welfare benefits. It is quite extraordinary the lengths these people will go to make people who are down on their luck feel like scum.
To get suggestions on how to view clips on The Daily Show and The Colbert Report outside the US, please see this earlier post. This clip appeared on February 2, 2012.
Most of us think that people who have made a ton of money by various means then simply invest it and live off the resulting income. But what form does this investment income take? If you are an average person, you tend to think of investment income as the interest on certificates of deposit or savings and money market accounts, which are taxed at the same rate as ordinary income. More sophisticated investors get their investment income in the form of [Read more…]