The probability that a point chosen at random in the triangle is also in the blue square can be calculated using geometrical definition of the probability:
[tex]Pr=\dfrac{\text{desired area}}{\text{total area}}.[/tex]
1. Find the total area of the triangle:
[tex]A_{total}=\dfrac{1}{2}\cdot 6\cdot 9=27\ in^2.[/tex]
2. Find the desired area of the square:
[tex]A_{desired}=3\cdot 3=9\ in^2.[/tex]
Then the probability is
[tex]Pr=\dfrac{9}{27}=\dfrac{1}{3}.[/tex]
Answer: correct choice is B
