Answer
$\dfrac{6}{7}$ or, $85.7 \ %$
Work Step by Step
The probability that the point $T$ lies on the segment $\overline{AC}$ can be computed as:
$P(T \in \overline{AC})=\dfrac{AB}{AD}$
Where, $AC=9-3=3$ and $AD=10-3=7$
Now, $P(T \in \overline{AB})=\dfrac{AC}{AD}=\dfrac{9-3}{10-3}=\dfrac{6}{7}$ or, $85.7 \ %$
