# What is the z-score of sample X, if n = 225, mu= 90, St. Dev. =90, and E[X] =78?

Jun 29, 2016

$1.5$

#### Explanation:

Z-Score

= (n - μ)/σ

= $\frac{225 - 90}{90}$

= $\frac{135}{90}$

= $1.5$

Plug into z-score formula. $n$ is your variable, μ is the mean, and σ is the standard deviation.