NO.PZ2022071202000090
问题如下:
Question选项:
A.1.90. B.0.29. C.0.94.解释:
Solution
C is correct.
In this case we have:
= (200 - 185)/(2678.05/25+2678.05/18)0.5
= 0.93768 ~ 0.94
A is incorrect. The mistake is to divide 2678.05 by 43 (25 + 18) and use the square root of the result as the divisor for the t-statistic: (200 - 185)/(2678.05/43)0.5 = 1.90.
B is incorrect. The mistake is to take an equally weighted average of the given standard deviations and use this as the divisor for the t-statistic: (200 - 185)/[(45 + 60)/2] = 0.28571.
这道题涉及的是哪个知识点,common variance在这里有什么意义?