The slope at the free end of a cantilever beam subjected to a point load at the free end is given by:
\[
\theta = \frac{M_{\text{total}} \cdot L}{EI},
\]
where:
- \( M_{\text{total}} = 10000 \, \text{N.m}^2 \) is the total area of the bending moment diagram,
- \( L \) is the length of the beam, and
- \( EI = 200 \times 10^6 \, \text{N.m}^2 \) is the flexural rigidity.
We also know that the total moment at the free end is given by:
\[
M_{\text{total}} = \frac{P \cdot L}{4},
\]
where \(P\) is the point load applied at the free end.
Thus, the magnitude of the slope at the free end is:
\[
\theta = \frac{10000}{200 \times 10^6} = 50 \, \mu\text{rad}.
\]
Thus, the magnitude of the slope of the beam at its free end is:
\[
\boxed{48 \, \text{to} \, 52 \, \mu\text{rad}}.
\]