Fridays Killer Questions 7city Learning:

Question)  You’re trying to get to Truthtown. You come to a fork in the road. One road leads to Truthtown (where everyone tells the truth), the other to Liartown (where everyone lies). At the fork in the road is a man from one of those towns -- but which one? You get to ask him one question to discover the way. What’s the question?

Daniel Kahneman - Thinking Fast and Slow

1) A bat and ball cost $1.10.
2) The bat costs one dollar more than the ball.
3) How much does the ball cost?

x+y=1.1; x=cost of the bat, y=cost of the ball.
y=x+1; substituting for y
x+(x+1)=1.1;
2x=0.1;
x=0.05; the cost of the ball
y=1.05; the cost of the bat

The right answer is 5 cents.
The intuitive, appealing, and wrong number is, of course 10 cents.

dicing-with-death-chance-risk-and-health (Stephen Senn)

Mr Brown has exactly two children. At least one of them is a boy. What is the probability
that the other is a girl?

What could be simpler than that? After all, the other child either is or is not a girl.
I regularly use this example on the statistics courses I give to life scientistsworking
in the pharmaceutical industry. They all agree that the probability is one-half.

So they are all...

As usual I am going to use this blog post to complain!
How can anyone in their right state of mind create a Finance Package
with out procedures for return calulation ie first difference, percentage change, log returns etc

This does not make any sense to me :-)

restart:
A := Matrix([[seq(i, i = 1 .. 10)], [seq(i, i = 11 .. 20)], [seq(i, i = 21 .. 30)]]):
A[.. -1,..] ;
A[.. -2,..] ;



You would assume that A[..-1,..] would remove the last row but that is not the case!
Instead you have to do A[..-2,..] he he it seems a bit odd!