The test statistic
\(\style{font-family:Times New Roman;}{\frac{{\overline X}_1-{\overline X}_2-\Delta_0}{\sqrt{\frac{\sigma_1^2}{n_1}+\frac{\sigma_2^2}{n_2}}}}\)
follows a standard normal distribution if:
◦
\(\style{font-family:Times New Roman;}{n_1\geq30}\)and the samples are dependent.
◦
\(\style{font-family:Times New Roman;}{n_2\geq30}\)and the samples are dependent.
◦
both\(\style{font-family:Times New Roman;}{n_1}\)and\(\style{font-family:Times New Roman;}{n_2\geq30}\)and the samples are dependent.
◦
both\(\style{font-family:Times New Roman;}{n_1}\)and\(\style{font-family:Times New Roman;}{n_2\geq30}\)and the samples are independent.