The standard deviation formula may look confusing, but it will make sense after we break it down. In the coming sections, we'll walk through a step-by-step interactive example.

The formula we use for standard deviation depends on whether the data is being considered a population of its own, or the data is a sample representing a larger population.

Standard deviation measures how far apart numbers are in a data set. Variance, on the other hand, gives an actual value to how much the numbers in a data set vary from the mean.

See how distributions that are more spread out have a greater standard deviation.

We learn how to calculate the mean and standard deviation of a discrete random variable. The concept of a random variable is explained, along with methods to calculate its expected value …

A z-score is considered unusual if it falls beyond a certain threshold, typically around ±2 standard deviations from the mean. However, the exact definition of "unusual" may vary depending on …

Practice calculating and interpreting the mean and standard deviation of a discrete random variable.

The standard deviation (sigma) is a measure of how much the data is spread out around the mean, not a better guess as to what the mean should be. A small value of sigma indicates that …

Find the standard deviation of the data set. Round your answer to the nearest hundredth.

What is the average age of the bears at your zoo? What is the standard deviation? Round your answers to the nearest tenth.