To find the measure of \( \overline{AC} \), we need to analyze the information given.
The segment \( \overline{AB} \) is given as 22.3 millimeters, and point \( B \) is the midpoint of line segment \( \overline{AC} \). Since \( B \) is the midpoint, it divides \( \overline{AC} \) into two equal parts: \( \overline{AB} \) and \( \overline{BC} \).
Therefore, the length of \( \overline{AB} \) is equal to the length of \( \overline{BC} \): \[ AB = BC = 22.3 , \text{mm} \]
The total length of \( \overline{AC} \) can be calculated as: \[ AC = AB + BC = 22.3 , \text{mm} + 22.3 , \text{mm} = 44.6 , \text{mm} \]
Thus, the measure of \( \overline{AC} \) is 44.6 millimeters.
The correct response is: The measure of \( \overline{AC} \) is 44.6 millimeters.