Thursday, August 21, 2008

Logarithms

if x = an then equivalently logax = n

Brain Teaser

Me, Springer, and Rabbit are travelling, and have to stop at a motel. We get a suite that is only 30 bucks, and we each pony up a 10 spot to cover our share.

when we get upstairs, the bell hop tells us there was a mistake, and the room will only be 25 bucks. he returns 1 dollar to each of us, and keeps 2 for a "tip" ((1+1+1)+2)=5 bucks).

So...we each spent 9 bucks (as we each recieved 1 dollar back on our original 10 dollars spent):

9X3=27

And the bell hop kept 2 bucks:

27+2=29

But we originally gave up 30.

where did the other dollar go?

Monday, February 25, 2008

Interest

p = i / (r*t)
i = p * r * t
r =
t = i / (p * r)

a = p(1 + r/n)nt