Are You Smarter Than A Fifth Grader?: The Pro-Obama Argument From A Younger Generation.

In order to make ends meet in these challenging financial times, I have begun tutoring kids and teaching SAT prep classes on the weekends for a company in San Diego. This weekend I worked with a very bright fifth grade boy on his writing (I have no idea why his parents are making him go to tutoring on the weekends– it just makes his bored in class for the rest of the week– but that is a discussion for another time). When I gave him the “opportunity”  to write a paragraph about anything he wanted, he chose to write about why Barack Obama is a good leader. His father is an Obama supporter and they have been watching the news coverage and debates together. Once he had decided on that topic, he was considerably less sullen about the task and I was pleased as well. I tried not to let my politics show too much, though; I’ve been running into people of various political leanings in my work and life lately and I figured it may be unprofessional. So, I resisted the urge to pull out my “Hope”, “Change”, and “Obama/Biden” stickers to help him decorate his paragraph and let him do it on his own. Here are his thoughts on why Barack Obama is a good leader.

“I believe Obama is a good leader. He is friendly and a peace-builder. Plus, he voted for wealth for everyone. Also, he is a great rolemodel. He is a self-confident man that is able to explain problems or things so easily even a baby could understand. He also wants to stop the useless war (that Bush started) in Iraq. But the problem with both candidates is that they do not explain who Joe the Plumber or Joe Sixpack is. If Obama wins he’ll be a great leader.”

Sounds good to me! I’ll see you all on November 4th.

algorithmic analysis

You have eight identical keys. One is heavier than the rest. Using nothing but a balance, what is the most efficient way to find it?

Solutions:

The most obvious answer is to split the keys into four groups of two, weigh each set individually, and in a maximum of four attempts you’ll have your answer. A rung above is the divide and conquer approach.  Split the keys into two groups of four on the balance, take the heavier four, split them in half, determine which two are heavier then weigh them against each other. Same answer, three steps, but it can be done in two. You split the keys into three groups, two sets of three and one set of two. Put the groups of three on the balance, if they are equal weigh the two remaining balls against each other. If they are not equal, balance two keys from the heavier side and take the third one out,  if one is heavier you have your key, if they balance you know the one left over is the heaviest.

The applied principle exploits the additional information provided by the balance. By splitting the keys into three groups and comparing two of them we can infer the state of the third. So the balance provides three pieces of information instead of two. In the worst case using this additional piece of information will always be 33% more efficient.

Demo (executable)

Demo (java Source)