AP Statistics Question (This was on one of my class tests)

Calculus
Thu, 08 Feb 2007 16:52:55 +0000

She said the same thing “It has to be between -1 and 1,” but I was arguing with her. I looked up in the book the definition of a zero standard deviation, which was roughly “all values are the same” which makes sense. So I can prove it’s a 0 sd for y, which goes into the equation as divide by 0. So that makes it undefined. Also the TI-89 says the same thing.