# What is the z-score of sample X, if #n = 256, mu= 67, St. Dev. =80, and mu_X =56#?

##### 1 Answer

Apr 22, 2016

It is -2.2. That means that you are between 95-97% of the curve probability density function.

#### Explanation:

It is -2.2000. That means that you are between 95-97% of the curve probability density function.

It is calculated using, assuming you random variable is normal, otherwise you should use the t-student, which is similar, but with a "fatter" tale:

This formula is value for N samples from a normally distributed random variable, with known stDev and meam, which was given in the question heading.

**See also**

* z-scores in Matlab