Monthly Archives: January 2012

All the M&Ms You Want

Teachers of statistics know that a bag of M&M candies is often the best resource available for discussing practically any topic in the curriculum. In honor of “no sweets” week here at school, I created a virtual bag of M&Ms. You can set the size of each bag (in number of candies less than 100) and you’ll get an assortment of blue, orange, green, yellow, red, and brown candies that follows the officially stated distribution for milk chocolate M&Ms!

The Limit Doesn’t Exist!

This is the finale of the math competition scene in Mean Girls. I can only guess that references to this scene are ubiquitous in calculus classes these days (either to the delight or exasperation of calculus teachers).

Here’s a graph of the actual function, referred to in the movie as an “equation”.

High Temperature

When the current temperature is greater than the predicted high temperature for the day, why doesn’t this report get updated? Is there a benefit in comparing the current temperature to the predicted high? Later in the day, wouldn’t it also be beneficial to know what the actual high for the day was?

Word Count

One of the neat WordPress plug-ins I use is Word Stats. Prior to this post, I had apparently written over 25,000 words for this blog. That’s half way to a NaNoWriMo novel! My favorite word seems to be “that” followed by “this”. The only “math” words to crack the top 20 are “number”, “numbers”, and “triangle”.

I wonder how the Word Stats plug-in handles the mathematical notation I often use. For example, is the phrase “a + b” considered to be three words?

Poker Probabilities

Poker probabilities are fairly straight forward to calculate or to look up in WolframAlpha. However, those probabilities assume a five-card hand. Most popular poker games allow a player more cards in order to make the best five-card subset.

For example, the most widely played poker game Texas Hold ‘em allows players the possibility of using a total of seven cards to make the best five-card hand. So does seven-card stud. Omaha Hold ‘em allows a maximum of nine cards, while in Triple Draw, a player could potentially see thirteen cards before making a poker hand.

I wonder how these different games change the five-card probabilities of respective hands, and it would be interesting to see if it changes how any of the hands stack up in relation to each other.

Sum Equal to Product

When I was exploring the tangent identity a couple weeks ago, I thought that one of the more peculiar aspects of it was that the sum of three numbers was also equal to the product of those three numbers. After all, among the integers this is only true of (0, 0, 0), (1, 2, 3), and (-1, -2, -3).

But as it turns out, this is so common among the real numbers that given any two real numbers x and y, there is a third number z such that x + y + z = xyz as long as xy ≠ 1. This is fairly easy to show with some algebra.

What does a plot of all these points (x, y, z) look like? Let’s turn to WolframAlpha to give us a 3d graph:

I expected the above to be a little more interesting until I realized the boundaries were too narrow. Here’s a better look:

Interesting!

How Many Balloons?

How many balloons are these two men carrying? Questions like this just come to mind when I’m walking down the street.

If I could have a mundane superpower — a knack or skill that is extremely useful but much less impressive than flying, invisibility, or super strength — I would choose to be an amazing estimator. If I could accurately estimate any quantity or measurement, I think I could do a lot of good.

A Leap Year

2012 is a leap year, meaning that an additional day is added to account for the fact that the actual time it takes for the Earth to make one revolution around the sun is slightly more than 365 days. A leap year occurs every four years with one exception: a year that is divisible by 100 is a leap year only if it is also divisible by 400.

I recently learned that the Chinese calendar has a different definition for a leap year. The Chinese calendar is primarily a lunar calendar. That means that months are determined by the phases of the moon. Specifically, the start of each month always occurs on a new moon. A typical year has twelve months and 353, 354, or 355 days. The correction to account for the difference between a Chinese calendar year and an astronomical year is a little more drastic: every so often, a new month is inserted because there will be thirteen new moons within a year.

Complicating matters even further is a rule that states the winter solstice must occur in the 11th month. Therefore, the point in the calendar where the new month is added will vary from leap year to leap year. How often do leap years occur in the Chinese calendar? The intervals are not regular, but it’s once every three years!