# On a standard measure of hearing ability the mean is 300 and the standard deviation is 20. What is the z-score for a person who scores 260?

Using the formula $z = \frac{x - \overline{x}}{s}$ where $x$ is the data point you're evaluating, $\overline{x}$ is the mean of the data set, and $s$ is the sample standard deviation, we plug in the numbers were given to get:
$z = \frac{260 - 300}{20} = - 2$