## Sunday, 28 February 2010

### Sunday Morning Math and Coffee

Sunday morning in East Anglia, and I am sipping my coffee as I read through some of my favorite blog sites... Do get over to Concurrencies where Steve Phelps has put up his favorite math movie, a really great explanation of Mobius transformations that should be seen by more HS students.

And since I have several blogs about coincidences, I should point out that Jon Ingram, also here in England somewhere (sorry Jon), has a nice simple problem about coincidences as well at his "Lessons taught, Lessons learnt" . Here is a teaser to get you started, right from Jon's page...

The average of a set of 64 numbers is 64.
The average of the first 36 numbers is 36.
What is the average of the last 28 numbers?

Then he very nicely answers the question:

Solution

The total of all 64 numbers is 64 X 64 = 4096.
The total of the first 36 numbers is 36 X 36 = 1296.
The total of the last 28 is therefore 4096 - 1296 = 2800,
which makes their average 2800/28 = 100.

and adds, "and is it a coincidence that 64 + 36 = 100?"

OH! and I couldn't remember this, or where I saw it, but I found it again on Jon's blog... did you know that "1% of a day plus 1% of an hour is exactly 15 minutes"??.
Time for a refill, and then to touch off the notes on my next post...