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Printjmc
counting and probability senior
Problem
Point is randomly picked from the rectangular region with vertices at and . What is the probability that ? Express your answer as a common fraction.
Solution
To see which points in the rectangle satisfy , we rewrite the inequality as . This inequality is satisfied by the points below the line . Drawing a line with slope and -intercept 0, we obtain the figure below. We are asked to find the ratio of the area of the shaded triangle to the area of the rectangle. The vertices of the triangle are , and , so the ratio of areas is
Final answer
\frac{287}{4020}