An analyst collects the following data related to paired observations for Sample A and Sample B. Assume that both samples are drawn from normally distributed populations and that the population variances are not known.

|**Paired Observation**|**Sample A Value**|**Sample B Value**|

|1| 25 18

|2| 12 9

|3| −5 −8

|4| 6 3

|5| −8 1

The *t*-statistic to test the hypothesis that the mean difference is equal to zero is *closest* to:

Question: can i use ba ii plus to calculate sample variance or standard error on this one?