# Off on a Tangent 17.7

## Was that test too easy?

Did you ever take a class where you (and most everyone else in the class) received an A without really working that hard? Well that class was too easy. Or maybe you took a class that was a little out of your comfort zone and despite working really hard you ended up with a D. Sounds like that class was too hard.

Just like Goldilocks, you need a class that is just right. But what is just right?  According to researcher Robert Wilson, a test that is just right (or one that leads to optimal learning) is one in which you score 85%. He calls this the 85% rule for optimal learning. For more information on this, you can read the entire research article here or read a shorter report on the article in Scientific American here.

[Editor’s Note: The average score on my statistics quiz this week was 85% as was Prof. Cinzori’s Multi 2 quiz—just right!]

## A most unexpected answer to a counting puzzle

Christian Forester alerted us to this video that gives a very surprising answer to a physics/math problem.

## Problem of the Fortnight

In honor of the newly redefined kilogram, we give you the following problem to begin the semester.

Anna Berington, one of the 2018 Iditarod mushers, has five dogs — Abby, Betsy, Charlie, Danny, and Ebeneezer — who have peculiar dietary constraints. Each must consume a whole number of kilograms of food every day, and Betsy needs one more kilogram than Annie, Charlie needs one more kilogram than Betsy, Danny needs one more kilogram than Charlie, and Ebeneezer (the lead dog) needs one more kilogram than Danny.  The butcher gives Anna 12 packages of scraps whose weights are: 2, 2, 2, 2.5, 2.5, 3, 3, 3, 3, 3.5, 4, and 4.5 kg.  The butcher wrote “Ebeneezer” on one of the 2-kg packages and “Betsy” on one of the 3-kg packages, so Anna gave those packages to those dogs.

Given the Anna satisfies the peculiar dietary constraints of her dogs, as well as the butcher’s wishes for the two specially marked packages, which dog got the 3.5-kg package?

Write your solution (not just the answer) on a sheet of butcher paper and drop in the Problem of the Fortnight slot outside Professor Mark Pearson’s office (room 212 in The Werf) by 3:00 p.m. on Friday, January 25.  As always, be sure to include your name and the name(s) of your math professor(s) — e.g. Thu Nome, Professors Balto and Togo– on your solution.  Good luck and have fun!