单选题
A square dart board has four dark circular regions of radius 3 inches，as shown in the design above．Each point on the dart board is equally likely to be hit by a dart that hits the board．What is the probability that a dart that hits the board will hit one of the circular regions?
A square dart board has four dark circular regions of radius 3 inches，as shown in the design above．Each point on the dart board is equally likely to be hit by a dart that hits the board．What is the probability that a dart that hits the board will hit one of the circular regions?
【正确答案】
A
【答案解析】如上面的图样所示，1个正方形的标枪板上有4个半径为3英寸的圆形的黑色区域。标枪击中标枪板上的每个点的概率相同，击中标枪板的标枪击中4个圆形区域中的某一个的概率是多大?
该题其实是问4个圆形区域的面积占标枪板的总面积的几分子几，这个分数就是击中标枪板的标枪击中4个圆形区域中的某一个的概率：
[*]
该题其实是问4个圆形区域的面积占标枪板的总面积的几分子几，这个分数就是击中标枪板的标枪击中4个圆形区域中的某一个的概率：
[*]