# Mean and standard deviation of a discrete random variable

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

## Example: Ticket sales for a concert

Organizers of a concert are limiting tickets sales to a maximum of $4$ tickets per customer. Let $T$ be the number of tickets purchased by a random customer. Here is the probability distribution of $T$:

$T= \# \text{ of tickets}$ | $1$ | $2$ | $3$ | $4$ |
---|---|---|---|---|

$P(T)$ | $0.1$ | $0.3$ | $0.2$ | $0.4$ |

**What do you think is the best interpretation of the standard deviation that you found in the previous question?**

Feel free to discuss this in the comments! Keep in mind that standard deviation describes how far away from the mean data points tend to fall.