NO.PZ2023091601000060
问题如下：
Using a sample size of 61
observations, an analyst determines that the standard deviation of the returns
from a stock is 21%. Using a 0.05 significance level, the analyst:
选项：
A.Can conclude that
the standard deviation of returns is higher than 14%.
Cannot
conclude that the standard deviation of returns is higher than 14%
Can conclude that
the standard deviation of returns is not higher than 14%.
None of the above.
解释：
The required test for
testing the variance is the chi-squared test.
To test whether the
standard deviation is higher (H0: standard deviation is lower than or equal to
14%), the critical value of chi-squared will be 79.08 (using df = 60 and p =
0.05). Since the test statistic is higher than the critical value, the analyst
can reject the null hypothesis and concludes that the standard deviation of
returns is higher than 14%.
critical value of chi-squared will be 79.08
