Arithmetic mean of $2$, $1$, $9$, $-3$, $\frac{5}{2}$

Find the arithmetic mean of $2$, $1$, $9$, $-3$, $\frac{5}{2}$.

The arithmetic mean of data is given by the formula $\mu = \bar{x} = \frac{\sum_{i=1}^{n} x_{i}}{n}$, where $n$ is the number of values and $x_i, i=\overline{1..n}$ are the values themselves.

Since we have $5$ points, $n = 5$.

The sum of the values is $2 + 1 + 9 - 3 + \frac{5}{2} = \frac{23}{2}$.

Therefore, the arithmetic mean is $\mu = \bar{x} = \frac{\frac{23}{2}}{5} = \frac{23}{10}$.

The arithmetic mean is $\mu = \frac{23}{10} = 2.3$A.