Answer
$\dfrac{3}{8}$
Work Step by Step
We can see that the area of the square is $\dfrac{A}{4}$, and the area of the shaded region is equal to half of the area of the square, that is, $\dfrac{A/4}{2}=\dfrac{A}{8}$.
So, the probability should be equal to the area of the shaded region and the area of the greater triangle.
This means that $P=\dfrac{3/8 A}{A}$
or, $P=\dfrac{3}{8}$
