# Thread: Stats: probability and zscores help

1. ## Stats: probability and zscores help

Im looking back over an old assignment and I cant figure out how to get the correct probability

Question: what is the probability of encountering a state with annul income less than ore equal to Maine?

Maine: (19590- 21856)/3537.59= - .64
(Maines income - mean) / standard deviation

go to the ztable, and the area associated with -.64 is .2611

then somehow I came up with a probability value of 26.43%, which is the correct answer but I have no idea how to get this probability value.

2. Originally Posted by cmf0106
Im looking back over an old assignment and I cant figure out how to get the correct probability

Question: what is the probability of encountering a state with annul income less than ore equal to Maine?

Maine: (19590- 21856)/3537.59= - .64
(Maines income - mean) / standard deviation

go to the ztable, and the area associated with -.64 is .2611

then somehow I came up with a probability value of 26.43%, which is the correct answer but I have no idea how to get this probability value.