The number line in the image shows an interval starting from 1 (inclusive) and ending at 5 (inclusive).

Interval Notation:

The interval includes both endpoints, so it would be: $[1, 5]$ This is because square brackets $[ \ ]$ indicate that the endpoints are included.

Set Notation:

In set notation, this can be written as: $\{ x \mid 1 \leq x \leq 5 \}$ This indicates the set of all $x$ such that $x$ is between 1 and 5, inclusive.

Do you want more details or have any questions? Here are 5 related questions for practice:

1. How would you write an interval that starts from $-3$ and ends at 4, excluding $-3$ but including 4?
2. What is the set notation for all real numbers greater than 2?
3. How does interval notation change if you exclude both endpoints?
4. What is the interval notation for the set $\{x \mid x > 0\}$?
5. How would you describe the interval $(-\infty, 3]$ in set notation?

Tip: Always use square brackets for closed intervals (including endpoints) and parentheses for open intervals (excluding endpoints).