The following data is available for two independent sample :

Then the value of t-statistic is :

-1.54

$n_1=8,\;n_2=10.$

$\bar{x}_1=191,\;\bar{x}_2=199.$

$s_1=10,\;s_2=12.$

$\text{For two independent samples:}$

$t=\frac{\bar{x}_1-\bar{x}_2}{\sqrt{\frac{s_1^2}{n_1}+\frac{s_2^2}{n_2}}}.$

$t=\frac{191-199}{\sqrt{\frac{10^2}{8}+\frac{12^2}{10}}}.$

$=\frac{-8}{\sqrt{\frac{100}{8}+\frac{144}{10}}}.$

$=\frac{-8}{\sqrt{12.5+14.4}}.$

$=\frac{-8}{\sqrt{26.9}}.$

$\sqrt{26.9}\approx5.186.$

$t\approx\frac{-8}{5.186}.$

$t\approx-1.54.$

$t\approx-1.54.$