## Friday, November 6, 2009

### Lazy blogging Friday

Yesterday, I posted a celebrity lolz, which is not my usual.

Today, I post a comedy Venn Diagram, which are relatively common on the Interwebs, though not at common as lolz cats. I think is the first time I've put one up.

I'm going to work on these. Some of them are excellent. Obviously, since I posted it, I think this one is pretty excellent. I laughed out loud at both spife and knork, as will all right thinking Americans.

More lazy blogging tomorrow, when I return to a mighty pillar lazy blogging, pretty girls.
~

Jess Wundrun said...

Ah, Venn Diagrams. I would like to see one that involves cereal. That would be the apex of interwebs coolness.

Totally off-topic: I am taking a financial management class. The teacher told us that to figure out how long it will take your money to double when invested somewhere, you divide 72 by the number of points you are earning.

So, if your CD is earning 2% it will take 36 years to double your investment. Everyone in the class wants to know "why 72?". The teacher just says "that's math".

Could you answer this question before next Wednesday so I can act like a genius in my class? Will I attribute my source? Well........of course (ish)

Matty Boy said...

Hi, Jess. Your professor's method is just an approximation. For interest rates under 5%, dividing the percent into 70 works better than dividing it into 72. When you get to 6% earnings, dividing into 72 is a pretty good approximation. When you get to 10%, dividing into 73 is better. If you could get crazy return on investment like 30%, dividing into 80 is better.

Here's the real numbers for 1% to 5%.
1% doubles in 69.66 years.
2% doubles in 35.00 years.
3% doubles in 23.45 years.
4% doubles in 17.67 years.
5% doubles in 14.21 years.

If you have a calculator, the real answer is log(2)/log(1+n%), where n is your interest rate.

ken said...

And be sure you don't do the interest rate as a percentage. For 5% interest, that would be log(2)/log(1.05).

Jess Wundrun said...

Thanks guys!

Now I only wish I knew what a log was. (te he)