Explanation:
Representing inequalities on number line:
First of all we write the inequalities that are to be represented.
Let x represent the elevation of the miner at any time of the day.
The minimum elevation is 6 ft below the sea level. If we consider the sea level as 0 on the number line, the lower limit is -6.
The maximum elevation is 6 ft above the sea level. Hence the upper limit is 6.
The elevation throughout the day is represented by the inequality:
-6 ≤ x ≤ 6 and represented on the line as shown in the picture attached.
Note: The solid end points of the line at 6 and -6 means that 6 and -6 are included in the inequalities.