Percentages

You can view as many worked out examples as you want. First you are shown the question. Click Show Answer to view the answer.
Click Show another Example to view another example. The best way to master mathematics is by practice. But practice requires time.
If you don't have the time to practice, you can always view many practice problems completely worked out and become good at it too.

A data set is normally distributed with the *mean* value $\mu = 63.00$ and *standard deviation* $\sigma = 9.00$. What percentage of data values are less than $x = 58.00$

**Answer**

*z-score* of $x=58.00 = z = \frac{x-\mu}{\sigma} = \frac{58.00 - 63.00}{9.00}=-0.56$

The area under the *standard normal distribution curve* to the left of $z=-0.56$ is $0.2877$

The percentage of data values that are less than $x=58.00$ is $28.77$