Classic Dishes...

Thanks, Teach

My math teacher my last two years of high school was Wayne Cruzan. Helluva nice guy, he was the kind of teacher who would let you hang out in his classroom during lunch hour (and was cool enough that you wanted to). But he was a great math teacher, too. Gave great notes. You could take a snapshot of the blackboards at the end of the day, and those would be perfectly servicable notes for studying for a test.

I had Mr. Cruzan for Algebra II, and something we called Math Analysis, which was basically a combination of trigonometry and all of the other stuff that doesn’t really fit into algebra or geometry, like sets and sequences and matrices and probabilities and such.

I was just OK at algebra (I’m golden with the basic tenets, but when it comes to trig identities and such, I was too lazy to memorize what needed memorizing, so I skated by with B-‘s), but I was GOOD at Math Analysis. I ended up getting the highest grade in the three Math Analysis classes that year. I even beat out one of the valedictorians. That was satisfying, lemme tell you.

Anyhow, the reason I mention all of this is ‘cuz last night I was talking to someone, and they threw out a probability problem: “You have 11 pennies and 6 quarters in your pocket. You reach into your pocket and pull out a random number of coins. What is the probabilty of those coins totaling 82 cents?”

And immediately my brain started turning. “Okay, the only way to make 82 cents is with seven pennies and three quarters, so first you’d have to pull out ten coins, there’s a 1 in 17 chance of that. 17c10 will tell us how many different sets of 10 we can get, then we need to figure out how many sets of seven pennies there are in 11, and multiply that by the sets of three quarters….”

Anyhow, I won’t bore you with the details. But I was pretty damn surprised to find that 14 years after graduating from high school, I still more or less remembered how to do that problem.

So, Mr. Cruzan, if you’re out there: Thanks.

(If you care, it comes out to (1/17) * ((11c7 * 6c3) / 17c10), which rounds down to 825/41327, or a hair over 1 in 50.)

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