问题如下图：
选项：
A. 
B. 
C. 
解释：
1. 关于c 选项，pooled estimate 可否用于variance hypothesie或者z test ？
2. A 选项哪里错了？ pooled estimator 只适用于non normally distribution?
NO.PZ2018062016000141 问题如下 Whiof the following statements on a pooleestimator most appropriate? A.It's equality of the variances of two normally stributepopulations. B.It's estimate awn from the combination of two fferent samples. It conly usein Chi-squaretest B is correct. A pooleestimate is estimate awn from the combination of two fferent samples. It's usewhen testing the concerning fferenbetween means. A为何错
NO.PZ2018062016000141 问题如下 Whiof the following statements on a pooleestimator most appropriate? A.It's equality of the variances of two normally stributepopulations. B.It's estimate awn from the combination of two fferent samples. It conly usein Chi-squaretest B is correct. A pooleestimate is estimate awn from the combination of two fferent samples. It's usewhen testing the concerning fferenbetween means. 题目中combination of two fferent samples，这个表述是关联的吧？
NO.PZ2018062016000141 问题如下 Whiof the following statements on a pooleestimator most appropriate? A.It's equality of the variances of two normally stributepopulations. B.It's estimate awn from the combination of two fferent samples. It conly usein Chi-squaretest B is correct. A pooleestimate is estimate awn from the combination of two fferent samples. It's usewhen testing the concerning fferenbetween means. pooleestimate体是指什么啊
NO.PZ2018062016000141 问题如下 Whiof the following statements on a pooleestimator most appropriate? A.It's equality of the variances of two normally stributepopulations. B.It's estimate awn from the combination of two fferent samples. C.It's only usein t-test. B is correct. A pooleestimate is estimate awn from the combination of two fferent samples. It's usewhen testing the concerning fferenbetween means. 谢谢
请问A怎么翻译呀？C错在哪了，不就只在t分布时候提及吗？
