\[ {t - statistic{\text{ }}{T_{n - 1}} = {\text{ }}\left( {x - \mu } \right){\text{ }}\left( {s/\surd n} \right)} \]
\[t - statistic{\text{ }}{T_{_{n - 1}}} = {\text{ }}\frac{{\left( {x - \mu } \right)}}{{\left( {\sigma /\surd n} \right)}}{\text{ }}\]
Where: