Calculate the z-score and determine if the data point 250 is an outlier, given a mean of 81 and a standard deviation of 130.

Mean ($\mu$) $= 81$
Standard deviation ($\sigma$) $= 130$
Data point ($x$) $= 250$

The z-score measures how many standard deviations a data point is from the mean. The formula is:

Substitute the given values:

A common rule for identifying outliers is that a data point is considered an outlier if its absolute z-score is greater than 2 or 3.

• If $|z| > 2$, it's often considered an outlier.
• If $|z| > 3$, it's generally considered a strong outlier. In this case, the calculated z-score is 1.3. Since $|1.3|$ is less than 2 (and also less than 3), the data point is not considered an outlier.

The final answer is $\text{not outlier}$.