Construction of Perpendicular Bisectors

After drawing a line segment $AB$ of length $5 \mathrm{cm}$ with scale and pencil and by folding paper, the measure of each of the bisected parts of line segment $AB$ is 

In the figure, $\mathrm{AB}=10 \mathrm{cm}$ and $\mathrm{CD}$ is the bisector of line segment $\mathrm{AB}$. If  measure of $\mathrm{MB}=k \mathrm{cm}$, what is the value of $k$.

We can bisect any given line segment with a ruler and compass.

Construction of the perpendicular bisector of a line segment is not always possible.

Infinitely many perpendicular bisectors can be drawn to a given ray.