新GRE数学要点:Geometric Figures
Geometric Figures If a point is selected at random inside a geometric figure, then the probability that the selected point lies inside a particular region is the ratio of their areas:area of the particular region inside the figure/area of the whole figure.
Example:
The probability that a randomly selected point within the square lies inside the circle=area of circle/area of square=∏r2/(4r2)= ∏/4
Remember:
If the particular region is not completely inside the figure, then use only the area that is inside the figure.
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