NO.PZ202106160300001102
问题如下：
The relative frequency of AA rated energy bonds, based on the total count, is closest to:
选项：
A.10.5% B.31.5% C.39.5%解释：
A is correct. The relative frequency for any value in the table based on the total count is calculated by dividing that value by the total count. Therefore, the relative frequency for AA rated energy bonds is calculated as 85/806 = 10.5%.
B is incorrect because 31.5% is the relative frequency for AA rated energy bonds, calculated based on the marginal frequency for all AA rated bonds, so 85/(32 +25+85 +100 +28), not based on total bond counts.
C is incorrect because 39.5% is the relative frequency for AA rated energy bonds, calculated based on the marginal frequency for all energy bonds, so 85/(100+ 85 + 30), not based on total bond counts.
不记得哪一个章节学过这两道小题的知识点，请老师指导。谢谢
