Area of each small triangle is 1/4 of area of large triangle ABC.
Probability of the dot falling on triangle PQR is = 1/4
Probability of the dot falling on small triangle is = 1/4
Probability of the dot falling inside the triangle PQR is \(\frac{3}{4}-\frac{1}{4}=\frac{2}{4}=\frac{1}{2}\) less than that of outside the triangle.