Calculate the mean (x) of the data set.

Here are the solutions to the problems you sent.

1. Calculate the standard deviation of 2,3,3,4,5,5,7,7 and 9.

Step 1: Calculate the mean ($\bar{x}$) of the data set.
The data set is $X = \{2, 3, 3, 4, 5, 5, 7, 7, 9\}$.
The number of data points is $n = 9$.

$$\bar{x} = \frac{\sum x}{n} = \frac{2+3+3+4+5+5+7+7+9}{9} = \frac{45}{9} = 5$$

Step