習題：
Exercise:
Assuming the distribution of XYZ stock returns is a sample, what is the sample standard deviation?
XYZ Corp. Annual Stock Prices | |||||
1995 | 1996 | 1997 | 1998 | 1999 | 2000 |
22% | 5% | -7% | 11% | 2% | 11% |
A 7.4%
B 9.8%
C 72.4%
D 96.3%
解析：
Answer: B
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知識點：
Sample Mean and Variance
The sample mean is the sum of all values in a sample of a population divided by the number of observations in the sample. It is used to make inferences about the population mean.
The sample variance is the measure of dispersion that applies when we are *uating a sample of n observations from a population. Using n-1 instead of n in the denominator improves the statistical properties of s2 as an estimator of σ2.
