2. 外语
  3. A research scientist wants to study a certain attribute of dogs. It is estimated that approximately 5 percent of all dogs have t

A research scientist wants to study a certain attribute of dogs. It is estimated that approximately 5 percent of all dogs have t

admin2009-05-19  87
问题 A research scientist wants to study a certain attribute of dogs. It is estimated that approximately 5 percent of all dogs have this attribute. If the scientist wants to study a sample of N dogs having the attribute, approximately how many dogs should be screened in order to obtain the desired sample size?
选项 A、N/5.
B、5N.
C、20N.
D、105N.
E、120N.
答案C
解析 一科学家想研究狗的某种特性。据估计约有5%的狗具有这种特性。若这位科学家想把N只具有这种特性的狗作为一个样本来研究，那么为了得到期望的样本大小，大约需要筛选多少条狗?
解：本题的正确答案为(C)。设需筛选x条狗，则由题意可得：x×5％=N → x=20N
转载请注明原文地址:https://www.kaotiyun.com/show/mWkO777K
本试题收录于： GRE QUANTITATIVE题库GRE分类
0

GRE QUANTITATIVE

GRE

相关试题推荐
随机试题
最新回复(0)