Standard Deviation of Bakery Sales Data

A small bakery tracks the number of pastries sold each day over a week. The daily sales are as follows:

20, 22, 23, 21, 20, 19, 25

Using this data set, calculate the standard deviation of the daily sales.

The formula for standard deviation ($ ext{SD}$) of a sample is given by:

$$ ext{SD} =\frac{ ext{sqrt}( ext{sum}((x_i - ar{x})^2))}{n-1}$$

where $ar{x}$ is the mean of the sample, $x_i$ represents each data point, and $n$ is the number of data points.