NO.PZ2023091601000060
问题如下：
Using a sample size of 61observations, an analyst determines that the standard deviation of the returnsfrom a stock is 21%. Using a 0.05 significance level, the analyst:
选项：
A.
Can conclude thatthe standard deviation of returns is higher than 14%.
B.
Cannotconclude that the standard deviation of returns is higher than 14%
C.
Can conclude thatthe standard deviation of returns is not higher than 14%.
D.
None of the above.
解释：
The required test fortesting the variance is the chi-squared test.
To test whether thestandard deviation is higher (H0: standard deviation is lower than or equal to14%), 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 analystcan reject the null hypothesis and concludes that the standard deviation ofreturns is higher than 14%.
1.H0≤14，Ha＞14。 t＝135，大于t统计量关键值 拒绝域在右侧，拒绝原假设。 2.H0≥14，Ha＜14。 拒绝域在左侧，t＝135落在接受域。