IntMath Newsletter: zTable interactive graph, CK12 resource, range hood
By Murray Bourne, 04 Feb 2014
4 February 2014
In this Newsletter:
1. New zTable interactive graph
2. Resource: CK12.org
3. Math puzzles
4. Friday math movie: Complex numbers in math class
5. Final thought: Giving
0. Sorry about the dummy mail
After I sent the last IntMath Newsletter, I made some updates to the script. When testing it, unfortunately some of my test mails (which contained text like "Lorem ipsum dolor sit amet") went out to a small number of you. I'm very sorry about that!
1. New zTable interactive graph
Some students get lost understanding what normal probability distributions are all about. You can investigate the meaning of the ztable using this new interactive graph. 
Here's some background on the topic:
Normal Probability Distribution
And here's some background on the new applet:
2. Resource: CK12.org
CK12.org is a large collection of free math and science resources. There's lessons, selftesting quizzes, videos and interactive applets. As one of the students says:

It's worth a look!
3. Math puzzles
The puzzle in the last IntMath Newsletter asked about the percentage of pages in a book containing the number 5.
Correct answers with explanation were given by Michael, Nicos and Sai Krishna, and Sheldon had the right number of pages. It was interesting to see the different approaches taken by the solvers. Mathematics rarely has one "correct" way of going about things.
Also, some of you questioned whether "a 5" means "one 5 only" or "at least one 5". Interpreting math word questions is one of the biggest challenges people face  reading skills are important in math, too!
New math puzzle
I received a letter from John recently. His problem is a really interesting one because it involves many areas of mathematics. Here's what he wrote:
I am a consultant to cabinet manufacturers. I program their cabinet software to calculate and cutout their cabinet parts on CNC (computer numerical control) machines. A lot of cabinet companies create hoods that go over stoves that are curved on both sides and front. I need to calculate the joint of that curve as if it is laying flat. How do you calculate this?
Here is a picture of the hood.
When viewed from the sides, the curves are arcs of circles, and the very top of the curve is vertical.
The width of the front face at the bottom is 60 cm, at the top is 30 cm wide and the (final) height of the curved portion is 50 cm.
Basically what I need is a formula to plot the Y coordinate of the curve given the X or viceversa when the piece of sheet metal is laid out flat.
Once you have a solution, you are encouraged to make a model of it so you can be sure it works as expected. Take a photo of your model and upload it to Flickr, Dropbox or wherever, and embed the photo in your response (using something like <img src="LinkToYourImage">), or if that's too troublesome, email me your photo.
Leave your responses here.
4. Friday math movie: Complex numbers in math class
This is a very creative way to present a lesson  funny, too. 
5. Final thought: Giving
Everyone is searching for happiness, and too many people try to find it in gadgets, cars, or other physical objects. Winston Churchill said:
We make a living by what we get, but we make a life by what we give. [Winston Churchill]
Until next time, enjoy whatever you learn.
See the 4 Comments below.