单选题
The following shows the yearly returns of aggressive equity funds for four years: 1999=+5% 2000=+2% 2001=+1% 2002=-4% Assume that this distribution can represent either the population or a sample of aggressive equity funds. Calculate the population and sample standard deviation. Population Standard Deviation Sample Standard Deviation A. 2.73% 3.99% B. 3.09% 4.55% C. 3.24% 3.74%
【正确答案】
C
【答案解析】 Step 1. Calculate the mean monthly return =2%+(-4%)+1%+5%=4%,
M=1%. Step 2. Calculate the population standard deviation:
([(2%-1%)2+(-4%-1%)2+(1%-1%)2+(5%
-1%)2])(1/N)2=3.24%. Step 3.
Calculate the sample standard deviation: ([(2%-1%)2+(-4%-1%
)2+(1%-1%)2+(5%-1%)2])/(n-1)2=3.74%.