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# Lesson Worksheet: Discrete Random Variables Mathematics

In this worksheet, we will practice identifying discrete random variables and using probability distribution functions and tables for them.

**Q9: **

Let be the random variable that represents the number of patients who visit a dental clinic per hour. The probability distribution of is shown in the table below.

10 | 11 | 12 | 13 | 14 | 15 | |

0.2 | 0.1 | 0.15 | 0.05 | 0.3 | 0.2 |

Find the probability of the following.

Exactly 13 patients visiting the clinic in a given hour

At least 13 patients visiting the clinic in a given hour

At most 13 patients visiting the clinic in a given hour