单选题
Independent samples drawn from normally distributed populations exhibit the following characteristics:
| Sample | Size | Sample mean | Sample standard deviation |
| A | 25 | 200 | 45 |
| B | 18 | 185 | 60 |
Assuming that the variances of the underlying populations are equal, the pooled estimate of the sample variance is 2,678.05. The t-test statistic appropriate to test the hypothesis that the two population means are equal is closest to:
【正确答案】
B
【答案解析】
B is correct. The t statistic for the given information (normal populations, variances assumed equal) is calculated as:
where
In this case we have:
