问题
单项选择题
An analyst takes a sample of yearly returns of aggressive growth funds resulting in the following data set: 25, 15, 35, 45, and 55. What are the range, mean absolute deviation (MAD), and sample variance of the data set range MAD variance（）①A. 2012 250 ②B. 25601000 ③C. 4012 250
A. ①
B. ②
C. ③
答案
参考答案：C
解析：
极差=最大值-最小值=55-15=40
[考点] 方差和标准差
0mL溶液，求氨水中NH3的物质的量浓度 (不考虑NH3与H2O的反应)。