正常成人发汞值呈偏态分布，描述其变异程度宜用
A．均数B．几何均数C．中位数D．四分位数间距E．标准差
参考答案：D
2014年中国CDC对全国人群乙型肝炎血清流行病学调查结果显示，15-29岁人群HBsAg阳性率为（）。
A、0.32%
B、4.38%
C、0.94%
D、3.39%
A sum of $200,000 from a certain estate was divided among a spouse and three children. How much of the estate did the youngest child receive ？（）
(1)The spouse received of the sum from the estate, and tile oldest child received of the remainder.
(2)Each of the two younger children received $12.500 more than the oldest child and $62,500 less than the spouse.
A.条件（1）充分，但条件（2）不充分.
B.条件（2）充分，但条件（1）不充分.
C.条件（1）和（2）单独都不充分，但条件（1）和条件（2）联合起来充分.
D.条件（1）充分，条件（2）也充分.
E.条件（1）和条件（2）单独都不充分，条件（1）和条件（2）联合起来也不充分.
of the sum from the estate, and tile oldest child received of 
the remainder.