# Math Help - Standard Deviation Help

1. ## Standard Deviation Help

What is the standard deviation of a normal distribution whose mean is 122 if a score of 170 corresponds to a z-score of 1.9?

2. ## Re: Standard Deviation Help

Originally Posted by khalyar
What is the standard deviation of a normal distribution whose mean is 122 if a score of 170 corresponds to a z-score of 1.9?
z-score = $\dfrac{x-\mu}{\sigma}$ where $\mu$ is the mean, and $\sigma$ is the standard deviation

$1.9 = \dfrac{170 - 122}{\sigma}$

solve for $\sigma$