**Assignment 9.4 Task + RSG.**In class notes on standard deviation

**Note**: The formula for standard deviation involves (Greek, "Sigma") or "sum" notation. refers to the *ith* element in the data set, is the *mean* x-value.

Reading this formula means:

- Find the difference between each value and the
*mean* - Square those differences
- Find the sum of all of the squares
- Divide that value by N (the number of data elements in the set)
- The Standard Deviation is the square root of the result

One way to understand the standard deviation is that it is kind of like the average distance from the mean in the data set.